D&D 3.5 to GURPS 4th Edition Conversion

by Bruce Grubb

Permission granted for strictly noncommercial use and distribution. AD&D 1st edition, AD&D 2nd edition and D&D3.5 are trademarks of Wizards of the Coast. GURPS is a registered trademark of Steve Jackson Games. This material is not official and is not endorsed by either Wizards of the Coast or Steve Jackson Games. The GURPS material here is used in accordance with the Steve Jackson Games online policy.

When I originally wrote guidelines to convert AD&D1 to GURPS back in 1987 I designed the conversions to as accurately reflect what AD&D1 characters were able to do in GURPS terms while keeping point cost down at the same time. Since then I have updated my conversions to bring them in line with the current versions of both games - D&D3.5 and GURPS 4th edition as well as making extensive use of the Web resources that now exist like GURPS Lite 4th edition and the GURPS Resource page

D&D class and levels vs. GURPS point levels

One of the main challenges in converting D&D3.5 characters and monsters to GURPS 4e is that GURPS provides a incredible degree of flexibility compared to the level and class system used by D&D3.5. The advantages of classes and levels is they provide a good starting point for beginners but at the same time they also set limits on what abilities a character can have ie only a Barbarian can Rage, Clerics and Paladins turn undead, Druids Wild Shape and so on. Also it is understood that certain skills are part of the class and so they get their host abilities outright or get bonuses in those areas (Fighters for instance start out knowing all simple weapons and get bonus feats) In GURPS the only limitations are the point total and what the GM will allow.

For these reasons you cannot relate a D&D level to a GURPS point total; the classes on their own simply vary too much in terms of GURPS advantages, disadvantages and skills to do that. Also GURPS has many tones of play ranging from “realistic” to high fantasy level cinematic. The tone has a large effect on what a character can do; a 150 pt cinematic character will have access to abilities and skills that would allow them to run rings around a 200 pt realistic character.

A related problem in conversion is they way the two games handle attributes. In GURPS attributes all start at 10 and can be adjusted by using points; however since IQ and DX determine the baseline of so many skills in GURPS these attributes are worth double what ST and HT are. But D&D uses a 4d6k3 method for generating stats which has an average of 12.176 compared to 10.5 for GURPS’ 3d6 making bonus level attribute scores more likely. These bonus adjustments are best represented by advantages in addition to modifying skill level.

However in D&D class and level determine what abilities or advantages are available and what the cost of extra-class skills are. In GURPS the level of the attribute, any related advantages, and the difficulty of the skill (Easy, Average, Hard, or Very hard) determine the cost of skill. So a INT 16 converts into less for a Fighter than for Wizard.

For these reasons I took the approach of giving options for adjusting attributes based on the disadvantages or advantages they grant. I then went through the classes and listed the abilities and limitations that most readily translated into GURPS terms. Finally I provided a way to translate modifiers into a GURPS skill level.

Since I first first put this out, Steve Jackson Games has put out the Dungeon Fantasy series (Adventures, Dungeons, The Next Level, and Sages) as ebooks. The Dungeon Fantasy series is more geared to creating a hack and slash campaign in GURPS from scratch than converting one. This page focuses on the conversion aspect.

Note: this page assumes you have at both books of the GURPS 4th edition Basic Set (whose page numbers are preceded by the letter ’B‘), GURPS 4e Fantasy (F), and GURPS Magic (M).


As stated at the start of this web page one aspect of D&D attributes that makes them hard to convert is that in addition to adjusting skills most of them confer what in GURPS terms would be called advantages (or if they are low enough disadvantages).

ST = STR (derived GURPS attribute HP)

While both D&D and GURPS use Strength for encumbrance the formulas are very different. D&D is more generous on light to medium encumbrance while GURPS is more generous on the heavy and extra-heavy side. Another problem is that in GURPS Strength rather than Health (CON or HT) is the basis for hit points. (for Hit Point adjustments given by CON consult the table under CON.) For these reasons is simpler just to use the D&D STR score. Not only do high Strength characters get better HP at low levels but since (ST^2) * 2 = x-heavy encumbrance they can carry more than they could in D&D.

DX = 10 + Dex modifier + relevant disadvantages and advantages

The related disadvantages and advantages DEX provides seem to best equate to the GURPS disadvantages and advantages Combat Paralysis, Basic Speed -/+4, and Combat Reflexes. So a -1 DEX modifier would result in DX 9 and Combat Paralysis/Basic Speed -1 and a +1 DEX modifier would result in DX 11 and Combat Reflexes/Basic Speed +1.

Related advantages: Flexibility (including Double Jointed), Enhanced Defenses, Perfect Balance.

IQ = 10 + INT modifier (derived GURPS attributes Will, Per)
See note on spell casters (Wizards).

Here we have another difference in the two systems. In GURPS all spells are IQ based skills with certain advantages providing bonues (or negating penalities) to learning them; by contrast in D&D the attribute that determines spells bonus is set by what class the character is. In GURPS terms this equates to advantage: Magery, Magery (Ritual), or Power Investiture and this is covered in greater detail in the GURPS magic systems in D&D page.

Note while learning languages in GURPS is relatively cheap GURPS does have something that is close to the language bonuses of INT - the Language Talent advantage.

Will = IQ + Wis bonuses/penalties

In GURPS terms Wisdom in D&D does a double duty; it determines what clerical spells a character can casts and it either improves or detracts from Will (an IQ derived attribute).

HT = 10 + Con modifier/(Dis)advantage (derived GURPS attribute FP)

In GURPS HT is the attribute that determines Fatigue Points (FP). In an D&D style campaign FP is going to be one of the players’ main concerns; combat costs (1 + encumbrance level) FP for every combat that lasts 10 seconds or longer (So a series of short battles will tire character out faster than one long one). The fun part is in under the default magic system in GURPS FP are also used to power spells so there is a trade off for all FP based spellcasters (called wizards in GURPS) between wearing armor and having FP to cast spells with. I have devoted a separate page to using GURPS magic in D&D which covers this and other issues in greater detail.

An interesting trade off one can do with converting CON to HT is the Unfit/Fit (dis)advantages. These (dis)advantages modify the HT roll but do not modify the attribute itself. So instead of CON 12-13 resulting in HT 11 you can have it equating to HT 10 and Fit instead. Some other advantages to look at are:

Damage Resistance (tough skin -40%), Rapid Healing, Hard To Kill, Resistant/Immunity and Regeneration. Remember that each advantage or level counts as +1 (ie Very Fit/Very Rapid Healing count as +2). Also some advantages may not fit with the concept of certain races.

D&D Hit points

This is the biggest problem in converting from D&D to GURPS; in GURPS terms D&D hit points represent a whole multitude of advantages, skills, techniques, and rules, some ‘realistic’ others most definitely cinematic in nature. Also unlike D&D even low point GURPS characters can if lucky take lots of damage. At 0 HP they make a HT roll each turn to stay conscious but do not have to make survival rolls until at -1*HP and multiples there after (until -5*HP where most characters die regardless and yes there are advantages that change this too).

So an average HT 10 HP 10 GURPS character would have a 50% chance of staying awake each turn at 0 HP or lower but would not be in danger of dying until they reached HP -10. Even if the optional bleeding rules (B420) are being used there is a 25% chance the GURPS character will stabilize on their own and even at -HP they would still have a 50% chance of making their survival roll. The higher the modified HT roll is the better these rolls become; this means that if the HT roll is creeping into the 15+ range than getting something to go down and die becomes increasingly difficult.

For example with an effective 14 the base chance a HT roll will succeed all the way down to -5*HP is only (.907^4) 67.7% while at 15 it jumps to (.954^4) 82.8% and at 16 goes up to a staggering (.981*4) 92.6%! (Since 17 and 18 always fail effective HT 17+ only matters if there are penalties to the HT roll). Note that this refers to an effective survival roll. HT 12 + Very Fit, HT 11 + Hard to Kill 3, and HT 14 all have the same HT survival roll though in other respects they are very different.

Of course as D&D classes increase in Hit Points more and more GURPS advantages, skills, techniques, and rules come into play. A good rule of thumb here is that GURPS’ standard ‘realistic’ advantages, skills, techniques, and rules will work reasonable well until roughly about 4 level. At that point the need for cinematic advantages, skills, techniques, and/or rules (B417) starts becoming pressing and at 8th level and above equivalent it is effectively mandatory.

Social Traits and Background

Here we get into an area where what information D&D does give us is not much help.


While the Charisma attribute in D&D determines physical beauty and natural leadership ability in GURPS these are totally separate. It is quite possible in GURPS to have a Very Handsome/Beautiful appearance and all the leadership ability of a rock or be totally hideous but have an outstanding ability to impress and lead others. For this reason Appearance and Charisma are separate in GURPS though they can reinforce each other or cancel each other out. Then there can be other things that effect how others see you. Having a Odious Personal Habit will cause reaction penalizes while having the Voice advantage results in a reaction bonus but only to things involving speaking or singing. Reputations can add or subtract from reaction rolls; Rank and Status can also modify reaction rolls.

Technology Level

Unlike D&D GURPS formally addresses the fact that differences in technology encountered will generally cause difficulty. Skills that are effected by technological differences are followed by a “/TL” (for example Traps/TL). Being only familiar with a lower TL then the campaign world is a disadvantage (it limits what skills you can learn at the standard TL) while conversely familiarity with a higher TL is an advantage.

In a realistic setting TL will not be uniform across the board which is why GUPRS provides four sample categories: Transportation, Weapons & Armor, Power, and Medicine each of which can have its own value. For example much of Christian Western Europe c1000 CE could be roughly called TL3 (Medicine TL1). Also one can have a familiarity with a higher TL than your own but not the ability to properly work on or repair such items; this is represented by TLx/y.

Then there is the notation TL(x+y) which denotes a TL that diverged from the path taken on Earth. This divergance means that while the TL is equivalent to the sum of (x+y) it looks little like that TL and in fact operating on different principles from the ‘standard’ TL. For example, if you really look at them most D&D worlds are at a level similar to but on a totally different path to the Renaissance-Age of Sail and Industrial Revolution periods of our earth diverging in the Middle Ages. This gives us TL(3+1) to TL(3+2) meaning that a character familiar with TL4 or TL5 will be at an additional -2 penality to use his TL based skills. In some case the differences will be so great that realisticly they can’t really use that TL based Skill. For example a TL(6+2) computer repairman familar with vaccum tubes would be totally lost trying to fix a TL7 transister based computer never mind a TL7 one based on the microchip.

Since TLs in any catagory grey into one other you can see TL(x+1) inventions side by side with TLy (where y=x+1) inventions though most will quickly become dead ends. One of the few real world examples of this is seen in comparing Edison’s 1898 Kinetophone to Lauste’s 1910 sound on film method. The Kinetophone (Speaking Mutoscope in GURPS Steampunk) is TL(5+1) in that it uses mechanical means so common to TL5 to sync picture and sound while Lauste used light and electricity that would become so common in TL6. For a brief time Kinetophone was superior to Lauste’s method eventually becoming the Videophone used in The Jazz Singer (1927) but as TL6 progressed Lauste’s method overcame its limitation and had quickly replaced Kinetophone/Videophone by 1935. Another example would be the Physics/TL(5+1) understanding of air dynamics the Wright Brothers and other would be airplane inventors had to deal with; the models were wrong and the Wrights along with everybody else had to invent Physics/TL6 air dynamics.

Finally there is superscience, technology that does not fit on the chart because it violates the current accepted cosmology which is marked with a ‘^’. D&D’s Spelljammer setting could be viewed as a TL(3+1)^ as it has some concepts involving a TL4 view of the cosmos but many of them are in TL3 terms. Magic allowing manned interplanetary travel (normally Transportation TL9) is noted by the superscience notation. Something similar happens with the Space 1889 setting but there you are dealing with an interesting mixture of TL5, TL6, TL(5+1), TL(5+2) and TL(6+1) with some superscience thrown in depending on what you are looking at. Verne’s famous submarine actaully uses TL(5+2) primary batteries which in the novel perform as well as TL7 nuclear power and Wells’ TL(6+1) atomic bombs in World Set Free continue exploding for years something the real TL7 bombs do not do. He was right though when he said “to this day the battle-fields and bomb fields of that frantic time in human history are sprinkled with radiant matter, and so centres of inconvenient rays” or what we would call fall out and radiation. But here again we are seeing TL7 expressed in TL(6+1) terms and in the real world the attitude toward the atom bomb by even those in the military (thanks in part to the propaganda of the period) as very TL(6+1)in that it was viewed as just a bigger explosion.


In D&D the INT one has determines the number of languages a character can know while GURPS has no such limitation. The default in GURPS is that a character knows how to speak as well as read and write one language natively. The cost of additional languages is based on how well they are known in both spoken and written form.


Wealth is always a problem - characters either have too little of it or too much. Written for GURPS 3rd edition Incanus Color of Money provides some ideas on how to deal with wealth from a point prospective.

Templates and Lenses

Because GURPS is so detailed and flexible it is easy to become overwhelmed by the choices. To help deal with this problem GURPS provides an option called Templates (B258-263) and a way to create common variations called lenses (B449). Templates come in three forms: Character/Occupational templates which serve a function similar to character classes in D&D, Racial which a package of advantages, disadvantages, and skills a particular race has, and finally meta-traits (B262-3, F133-4) which denote a particular state. Lenses are simply specialized templates that create an emphasis ie the Paladin and Ranger can be done as lenses of the Fighter template.

Racial Templates

Between the two of them the Basic Set and Fantasy provide a plethera of race templates ranging from the staple D&D races of Dwarf (B261, F107), Elf (B316, F108), Halfling (F109), and Orc (F110) to more exotic races like Centaur (F105), DevilFish (F105), Djinni (F107), Dragon (B261, F107), Faerie (F108), Felinoid (B261), Ghoul (F108), Imp (109), Myrmidon (F109), Selkie (F110), Troll (110-1), Eastern Vampire (F111), Gothic Vampire (B262), and Werewolf (F112). Then there are the undead lenses (F112-3).

As this list shows nearly anything can be made into a race template. As long as you deal with concepts rather than game mechanics it is surprisingly easy to sit down with the GURPS Basic Set in one hand and the Monster Manual in the other and make up race templates (GURPS Fantasy just makes the effort a little easier). The reason for this is simple; the wide range of rules and advantages allow greater flexibility in how to render a race than provided by D&D.

However that flexibility can result in information overload if you are not sure on where to go with a race which why references to the already created racal templates are provided. There was a Race Index at the GURPS website that was written for GURPS 3rd edition that with GURPS Update (found with other usefull links GURPS Resource page) can be brought up to the current edition with little problem.

That said usially converting a monster into a racial template or lens from scratch can take the monster into new directions you never thought of before. I should mention that there is a difference between a racal template and a lens. A racial template decribes a race of beings while a lens is a modifer of a racial or occupational template. For example, nearly all self willed undead are lens of whatever they were in life but they do fall into two groups (corporial and spirital) which are best handled by mega-trait templates. As an example I have provided an updated version of the Lich conversion which is significantly different from the version in GURPS Fantasy.

Since nearly anything can become a racal template or lens, the only limitations are what the GM allows the Players to use. A resourceful GURPS GM could even create an “Anti-Dungeon” where the players are playing brave monsters trying to defend their home from evil adventures!

Occupational Templates

Occupational Templates (also known as character templates) in GURPS generally include everything: Attributes primary and secondary, advantages, disadvantages, and skills. However in this conversion the Attribute section of such Templates has been taken care of so we are left with advantages, disadvantages, and skills. However unlike D&D GURPS skills can default to other skills, so you do not need to know as many skills as it may first appear. This is especially true of the Melee Weapons skills (B208-209) which come in six main categories three of which have generalized defaults but some weapon skills within these three categories default to weapons in other categories. As a result D&D’s weapon categories of simple, martial, and exotic have no meaning in GURPS. Also skills the classes logically should have are missing (Clerics for example do not have theology). For these reasons and to simplify the conversion while adding some flexibility I modified the D&D class templates to bring them more in line with their Medieval-Renaissance (TL3-4) inspirations as well as adding advantages and skills better suited to role-playing.

The noted exeption is the Monk; the D&D Monk owes more to 1970s Kung Fu movies than Medieval European Monks and IMHO to really due justice to the class the addition of GURPS Martial Arts would be needed. So to keep the book total down I provide an alternative monk more in keeping with the way they were - a person of people of learning whose efforts keep the old knowledge of the great fallen empire alive. If you want a Monk more along the lines of the D&D type there is the Wardancer (F126).

As with ‘standard’ GURPS Occupational Templates these class templates are customizable via lenses. To simply things I have used the Cleric, Fighter, Rouge, and Wizard classes as the baseline and made the other classes (except for the Monk and Bard) lenses of them. Since GURPS allows such a large range of variety there is no need to convert the NPC classes of Adept, Aristocrat, Commoner, Expert, and Warrior whose existence IMHO was barely justifiable to begin with.

Since attributes are separated from these Occupational Templates the skills only have one point rather then being at a particular skill level. Following each skill is the attribute/difficulty for quick reference. Optional abilities are ones the D&D class has but should be looked at before being used (which is why they have page numbers after them). Some Occupational Templates and Lenses also have a page reference if you want to use the totally different made for GURPS version in Fantasy. (Dungeon Fantasy Adventures has it own 250 point versions as well.)

Cleric [16] (Holy Man F120)
Clerical Investment [5], Blessed or Power Investiture [10], True Faith (15)
Duty [Church/Religion] [-10], Vow (varies) [-10]
Crossbow (DX/e), First Aid/TL (IQ/e), Theology (IQ/h),
Melee Weapons: Axe/Mace (DX/a), Knife (DX/e), and Spear (DX/a),
Occultism (IQ/a), Shield (DX/e), Spells (IQ/h to IQ/v), Throwing (DX/a)
Optional Advantage: Legal Immunity (B65)
Optional Skills: Esoteric Medicine (B192), Hidden Lore (B199), Physician/TL (B213)
Druid lens [+6]
You are a cleric of nature. Add Animal Handling (IQ/a), Naturalist (IQ/h), Pharmacy/TL (Herbal) (IQ/h), Survival (IQ/a), Tracking (IQ/a), Veterinary/TL (IQ/h)
Optional advantages: Animal Empathy (B40), Talent (Animal Friend) (B89-90)
Fighter [14]
Armoury/TL (IQ/a), Bow (DX/a), Brawling (DX/e), Crossbow (DX/e)
Melee Weapons: Axe/Mace (DX/a), Flail (DX/h), Knife (DX/e), Polearm (DX/a), Spear (DX/a), Shortsword (DX/a), Two handed Axe/Mace (DX/a), and Two-handed sword (DX/a),
Shield (DX/e), Throwing (DX/a)
Optional advantages: Enhanced Defenses (B51), Trained By Master (B93), Weapon Master (B99)
Optional Wildcard skill: Sword! (DX, B175)
Barbarian Lens [+0] (F116)
You are a fighter from one of the ‘Uncivilized’ parts of the world. Add Basic Speed [5/0.25], Low TL [-5/TL]; Language (native speaker, illiterate) [-3]
Running (HT/a), Strategy (IQ/h), Tactics (IQ/h)
Optional Advantage: Enhanced Defenses (Dodge, B51)
Optional disadvantage: Berserk (B124)
Paladin Lens [+45]
You are a warrior defender of the faith. Add Blessed or Power Investiture (powers lost if Chivalric and/or Religious Codes broken, severe penance) [10], Rep +2 (from Religion) [10], Status 2 [10], Comfortable Wealth or Patron [10], True Faith [15], Vow (Chivalric Code of Honor) [-15];
Riding (DX/a), Lance (DX/a), Heraldry (IQ/a), Savoir-Faire (IQ/e), Spells (IQ/h-v)
Optional advantages: Healing (B56)
Optional skills: Esoteric Medicine (B192), Hidden Lore (B199), Physician/TL (B213)
Ranger Lens [+11/+16]
You are fighter with an affinity with nature. Add Magery 0 [5] or Power Investiture [10];
Animal Handling (IQ/a), Hiking (HT/a), Naturalist (IQ/h), Survival (IQ/a), Tracking (IQ/a), Veterinary/TL (IQ/v)
Optional advantages: Animal Empathy (B40), Talent (Animal Friend) (B89-90)
Bard [28] (F117)
Magery [15];
Armoury/TL (IQ/a), Bow (DX/a), Crossbow (DX/e), Literature(IQ/h),
Melee Weapons: Axe/Mace (DX/a), Knife (DX/e), Spear (DX/a)
Innate Attack (DX/e), Musical Instrument (IQ/h), Poetry (1a), Public Speaking(IQ/a), Shield (DX/e), Singing (HT/e), Throwing (DX/a)
Optional Advantages: Legal Immunity (Bardic, B65), Talent (Music, B89-91)
Monk [0]
Legal Immunity (w/ Diplomatic pouch) [10]
Duty (Church/Order 12-) [-10], Vows [varies] [-10]; Diagnosis/TL (IQ/h), Esoteric Medicine (Per/h), First Aid/TL (IQ/e), History (IQ/h), Literature (IQ/h), Melee Weapon: Staff (DX/a), Naturalist (IQ/h), Survival (IQ/a)
Optional skills: Esoteric Medicine (B192), Hidden Lore (B199), Physician/TL (B213)
Rogue [13] (Thief F124)
Acrobatics (DX/h), Brawling (DX/e), Bow (DX/a), Climbing (DX/a), Crossbow (DX/e), Escape (DX/h), Lockpicking/TL (IQ/a), Melee Weapon: Knife (DX/e), Pickpocket (DX/h), Stealth (DX/a), Streetwise (1a), Throwing (DX/a), Traps/TL (IQ/a)
Sorcerer/Wizard [22] (F118-119, F124)
Magery/Magery (Ritual) 1 [15];
Alchemy/TL (IQ/v), Innate attack (Beam/Breath/Projectile) (DX/e), Melee Weapons: Axe/Mace (DX/a), Knife (DX/e), and Spear (DX/a), Spells (IQ/h-v), Thanumatology (IQ/v)
Optional Wildcard skill: Magic! (M202)

Converting Skills

D&D skills and feats translate into a mixture of GURPS advantages, skills, and/or cinematic rules. For the most part conversion is straightforward but there are several areas where it is not. Addressing the vagueness in these particular areas is the purpose of this section.

Craft and Knowledge all convert to the relevant GURPS skills. Profession is a special case as some are Professional skills (like tanner, tailor, etc) while others involve several GURPS skills (like farmer or lumberjack). Take farmer for example; in GURPS a farmer would obviously have the Farming/TL skill but skills like Carpentry, Cooking, Naturalist, Scrounging, Survival, and Tracking would also be relevant to a medieval farmer as would if location permitted Boating and Fishing. Lumberjack is another profession that at TL3-4 would have been made up of several skills: Climbing, Lifting, Naturalist, Tracking, and Two-handed Axe/Mace immediately come to mind.

Use magic device has no counterpart in GURPS as an enchanter can configure the requirements to use a magic item with Linking spells (M130-132).

D&D Skill GURPS Equivalent
Appraise Merchant (IQ/a, B209)
Bluff Fast-Talk (IQ/a, B195)
Decipher Script Linguistics (IQ/h, B205)
Disable Device, Search, Spot Traps/TL (IQ/a, B226)
Heal First Aid/TL (IQ/a, B195), Physician/TL (IQ/h, B213), Surgery/TL (IQ/v, B223)
Slight of Hand Slight of Hand (DX/h, B221)
used as default for PickPocket (DX/h), Holdout (IQ/a)
SpellCraft Ritual Magic (IQ/v, B218, M200), Thaumatology (IQ/v, B225), or Weird Science (Magic) (IQ/h, B228)

Feats are even more varied than skills are.

D&D Feat GURPS Equivalent
Armor Profiency Feats Fit or Very Fit Advantage (B55)
Weapon Profiency Feats covered partly by Techniques (B229-233), rest built into system.
Dodge, Expertise covered by Enchanced Defences advantages and Techniques.
Mounted Combat Techniques of Riding skill.
Point blank shot (all) Zen Archery (note Prequisites)
Power Attack (all) Trained by Master and/or Weapon Master
Brew potions Alchemy/TL (IQ/v) skill
Craft [item] Enchantment Spell + relevent craft skill
Metamagic feats None, built into GURPS Magic system

Converting Skill Levels

Here we have our biggest set of problems in converting characters. Unlike D&D GURPS not only has critial success and failure built into the system but there are on a sliding scale; in other words effective skill determines what die roles are critial success and failures. The linear d20 has a real problem with this compared to the 3d6; if we ignore the sliding scale, inconsistances in the DC table, the large differences in the combat (armor, damage, hit points, and combat round duration), and using an c1983 White Dwarf article combined the old ‘1 and 20 rule’ that many DMs used and was part of the AD&D 2nd edition rules (Under the 1 and 20 rule, 1 was always a failure and 20 was always a success.) we get this table:

 d20 20 19 19 18 16 14 11 10 7 5 3 2 2 1
  .019 .046 .093 .162 .259 .375 .500 .625 .741 .838 .907 .954 .981 .995
 3d6 3-4 5 6 7 8 9 10 11 12 13 14 15 16 17-18

However GURPS does use a sliding scale. If effective skill is high enough 5 and even 6 become critical successed while if effective skill is low enough 16, 15, and even 14 become critical failures. Adding to our problem in figuring out what a skill rank in D&D means in GURPS is the fact the DC examples in the DMG are all over the place partly due to differences in wha skills are handled. If this was not enough there are modifires based on the difficulty of the task (B345) as wells as the GURPS equivalent D&D’s take 10 and take 20 (B346).

The best solution to this situation is to note what skills the character has and figure out their base level based on the information on B171-172 and especially the “Choosing Your Skill Levels” box on B172. If you still think you need send your skill level past 20 look at the Techniques (B229-233, F136) as a way improve what the character can do rather than send the skill level into orbit.

With so many choices a few advantages and skills deserve mentioning:

Affliction (B35), Binding (B40), Innate Attack advantages (B61) and Innate Attack skill (B201)
One of these GURPS advantages and the Innate Attack skill is going to be your most used combination in converting D&D monsters because so many have it whether it be the crushing mandibles of a giant ant (Innate Attack), the web of a giant spider (Binding), the gaze of a medusa (Affliction), or the breath weapon of a dragon (Innate Attack). The advantage is the attack itself while the Innate Attack skill is hitting something with it. The Innate Attack skill is also used for certain spells.
The spell systems GURPS allows are detailed enough that they are dealt with separately in my GURPS magic in D&D page. The general advice here is to compare how spells function effectwise rather then focusing on individual spells. For example the D&D spell Leomund’s Secret Chest is roughly equivalent to the GURPS spell Hideaway while Detect Secret Doors and Detect Snares and Pits are roughly equivalent to one GURPS spell: See Secrets.
Trained by a Master (B93) and Weapon Master (B99)
These two advantages are similar in that they reduce the penalties for Rapid Strike and multiple parries and are the prerequisites for a host of cinematic skills. However they differ in several key areas. Trained by a Master has a larger skill list while Weapon Master not only allows more fine tuning (from one weapon all the way up to every muscle powered weapon in the game) but it reduces skill defaults for muscle power weapons and at high skill level actually adds to damage. Usually a character will have either Trained by a Master (most cinematic Kung Ku characters) or Weapon Master (Conan, Thundarr, and Zorro) though there are a few that have both like Scorpion of Five Deadly Venoms and Xena.
Unkillable (B95)
Nearly every high level Undead monster and many demons in D&D will have this advantage. Unkillable 1 allows the monster to remain fighting all the way to -10*HP without a single HT roll and Unkillable 2 and 3 allow the thing to come back! Dracula in the Hammer horror films had Unkillable 3 with the Achilles Heel (wood, running water), Hindrance (wood, frozen water), Trigger (blood) limitations.

The World, Universe, and Everything Else

You have converted characters (or used available templates) and now comes what can be the hardest: converting the world itself. As noted on B493 you only need to do the PC treatment of major NPCs; everybody else can pretty much be made on the spot so NPC conversion is not a problem. However world conversion can be especially difficult if you are dealing with modules of any kind.

This is where GURPS Fantasy become very useful as it will give you the tools to better convert an existing fnatasy world (as well as build one from scratch). Their are race template for many races and a few unique mythological characters such as Lilth (F54) and Tiamat (F56). However before you go head long into Fantasy it is still best to start with the Basic Set. Chapters 17-19 (B462-522) are definitly a must and here again GURPS goes into far more detail than D&D does. The concept of Contal Ratings and Legality Classes (B506-7) give the GM excellent tools for controlling potential bothersome spells and items; most D&D goverments with be in the CR3-5 range with the occational CR6.

Combat: fighting the good fight

The most important thing to remember about combat in GURPS is that if you are not careful it can become very deadly very quickly. Be careful in giving out advantages provide huge advantages in combat (Innate Attack, Weapon Master and Unkillable just to mention three) but also be wary of certain combinations which can create real headaches for your party. The high HT + Fit + Hard to kill combo is one potential problem as is Regeneration at high levels.