Par is calculated by the number of reasonable throws intended by the course designer for a first-class player of a particular skill level to reach “close range” then take two throws to hole out. Ordinary weather conditions are also assumed.
The PDGA skill levels are Gold, Blue, White, Red, Green.[1] Each skill level has an average drive length for a first-class player that is used as the main guideline for calculating par. This drive length is a length that a majority of the players of that level can throw with an average drive on a hole with average foliage.
Keep in mind that “effective length” is used instead of “actual length”. “Effective length” takes into account the effect of elevation changes[2] and forced lay ups. Forced lay-ups cause a shot to be shorter than the maximum distance; they can be caused by water carries, fairway bends such as L or S shapes, severe doglegs, and even extremely tight fairways or low ceilings. A forced lay-up is counted as one shot toward the basket. From that shot’s landing zone the course designer will determine how many more shots, if any, are needed to reach close range, then add 2 to complete the hole.
Fairway throws, used on multi-throw holes, are 80% of the length of tee shots. The fairway throw length is based on the reasoning that you lose approximately 20% of your driving distance when throwing from the fairway.
Close Range is the distance from which first-class players can get “up and down” in two about 90% of the time. It is much longer than the 10 meters used to define a disc golf putt. This is analogous to reaching the front edge of the green in traditional golf. Since disc golf holes usually take less than 2 putts to complete adding this close range component helps score averages to be closer to par.
Note that par is based on a “reasonable throw” along an intended flight path to a landing zone. One way to visualize this is to think of the flight path as a clear tube, with the shape of the intended flight path, extending from the tee to the landing zone. Everything inside of the tube is the intended flight path. Depending on the shape of the fairway and the proximity of foliage the tube may be large or small, very wide or very narrow. Since foliage, obstacles, or OB are outside of the tube they have no direct effect on the disc. If a player hits a tree or goes OB, no matter how high the percentage of times it might happen, then it was not a throw that went in the intended flight path. If the fairways seem too narrow or the flight path unreasonable or there is too high a risk of going OB then these are design issues, not par issues.
Many holes are not designed for the best shots to be made with enough power to reach the average drive length, though. A course designer can use narrow fairways, low ceilings, and nearby OB so that the smarter throw will be a shorter shot using a more controllable disc. In these cases the designer will determine reasonable throws that are intended to reach a landing zone that is shorter than that of designate CR length. On these holes par is the number of shots to reach each landing zone until one gets to close range then add 2 to hole out.
The following table gives the lengths of full power shots for each type of shot for each level.
Shot Lengths for each Level
Combining all of these throws gives the hole lengths for various pars at each level…
Close Range Par
The maximum effective length for par.
For example, on Gold level holes the base drive length is 400 ft., and the CR length is 100 ft. Therefore, for Gold level holes the maximum effective length for a par 3 is a 400 ft. drive plus a 100 ft. close range shot, for a total of 500 ft.
Since close range length is added to the drive length eagles will be very rare for holes at the maximum length. Keep in mind, though, that this only applies to holes at the maximum length, so most holes would most likely be shorter than this. On par 3 holes that are shorter than the drive length standard a drive can reach the basket, so they can be eagled.
Appendix
Examples
Here are a few example holes so that you can see how CR Par works. (All lengths are “effective length”):
1) On a Gold level course, if a hole is 530 ft. long, then a Gold level player would throw his drive 400 ft. and be left with 130 ft to the basket. Since that is longer than the 100 ft. Gold “close range” distance he is allowed one more throw in regulation and then 2 more throws to hole out. This is a very short par 4.
However, if the hole is 480 ft. long then the average Gold level drive of 400 ft. leaves only 80 ft, which is within “close range”, so this is a par 3, albeit a long par 3.
2) A 480 ft hole on a White level course: A first-class White level player has an average drive of 300 ft. and a close range distance of 80 ft., so the maximum length of a White par 3 is 380 ft. Since this hole is 480 ft., it’s a par 4.
3) A hole with a forced lay-up: On a Gold level course one of the holes is 460 ft. Normally a hole of this length would be a par 3, but it has an L bend at 200 ft., so the drive has a forced lay-up. From the drive’s landing zone the 2nd shot is down a corridor of trees with an OB stream all down the left side. The course designer intended for the 2nd shot to reward accuracy for those who use an approach disc with a shot of 240-260 ft. Since the 2nd landing zone is within close range the player has 2 more shots to complete the hole. Because it took 2 shots to reach CR this is a par 4.
Acknowledgments:
Thank you to Dave Marchant for his help in editing this document and providing many helpful comments that have improved it.
[1] Player Rating (PR) ranges for each Skill Level: Gold = 975-1025, Blue = 925-974, White = 875-924, Red = 825-874, Green = 775-824.
[2] Elevation changes are accounted for with every 1 ft. of elevation change equal to 3 ft. of length. Uphill shots increase the effective length and downhill shots decrease it. Ex.- A 10 ft uphill elevation change adds 30 ft onto the effective length.
There is also a file with this explanation that you can download from the Files section.