by Mike Shea on 28 September 2020
Sometimes it's useful to have a rough gauge of how many hit points we can expect D&D characters to have at any given level. Will our deadly trap be truly deadly? Will the dragon's breath weapon TPK the party? Every so often questions like this come up.
Granted, we can simply ask our players for their maximum hit points and work with that or we can keep a rough gauge of character hit points on hand. But, with the wide range of classes, constitution bonuses, and feats; how can we determine average hit points?
To answer this question I developed a simple Monte Carlo simulator of character hit points. This simulator determined the hit points for 200,000 randomly generated characters from 1st through 20th level across all classes. It includes weighted probabilities for constitution bonuses and the weighted likelihood that a character takes the toughness feat.
The table below summarizes these simulated characters with the median HP value across the 10,000 simulated characters of each level, their quartiles, the standard deviation, and a simpler equation of 7 x Level + 3 which ends up nearly as accurate up through 16th level and is likely good enough on its own.
|level||25%||50%||75%||std||7 x lvl + 3|
Much of the time we build our campaign worlds without regard to the characters' specific level of statistics. Instead, we let the situation dictate how the world works. Sometimes, though, we want to know if we're headed into a danger zone or whether something is going to be easier than the story dictates. In this case, it helps to know what the average hit points are at a given level. At the same time we don't want the world to react too closely to the characters. If we built it around the exact hit points of the characters, the world would overfit. Instead, we keep the average hit points in mind as a rough gauge to recognize when something might be too easy or too hard.
Keep the equation in mind of "7 X level + 3" as a rough gauge. When we want to know how powerful some trap, hazard, or monster is compared to the characters; use this equation to estimate the risk of the threat. We can also take comfort in knowing that it's pretty close to the more detailed simulation of 200,000 characters.
Keep such simple tools on hand to help you steer the game's focus on the story of your shared adventures.
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