Download the Demon's Souls Stat Planner by Hawu here.
This stat planner allows you to select your stats and class, allowing you to determine which class is best for your stat distribution. It also lets you select armor and weapons to determine equipment burden, magic defense, fire defense, physical defense, and bleed/poison/plague resist accurately. It also accurately predicts body form HP, soul form HP (at neutral or higher CT and WT), MP, miracle slots, magic slots, stamina, safe landing, item drop rates, and bare hand attack rating (if that's your thing).
You will also find three "quick-calcs" for your convenience. They are:
Soul Level Interaction Calculator - input soul level, output interaction
Soul Cost Calculator - input start and end levels, output soul cost
Soul Level Calculator - input souls and start level, output level
This planner does not have support for varying CT/WT levels and their relation to your HP. It also does not have completely accurate stamina regen penalties. These will probably not be updated, unless there are a lot of requests, and it's highly unlikely that will happen. For the attack rating of the equipped weapons, please use the online calculators accessible by the sidebar, or download the Attack Rating Calculator on this website.
Please click on the picture below to be redirected to the download page.
Link to be replaced 2nd week of August.
This file is in MS Excel 2007 format. If you use an older version of Excel, you may need to download the compatibility pack provided by Microsoft.