What this calculator does
A Dungeons & Dragons character’s hit points come from a simple, published formula rather than anything a dungeon master invents on the spot. At 1st level, HP equals your class hit die at its maximum, plus your Constitution modifier. Every level after that adds either the hit die’s average value (rounded up) or a rolled result, plus the Constitution modifier again. This dnd hp calculator runs that 5th-edition formula for any hit die, level and Constitution modifier.
The detail people get wrong is applying the Constitution modifier only once, at 1st level. It is added again at every subsequent level too, which is why a high-Constitution character pulls dramatically ahead in total HP as levels stack up, well beyond what the hit die alone would suggest.
The formula
Hit points at 1st level equal the hit die’s maximum value plus the Constitution modifier. Each level after that adds either the average hit die value, rounded up, or a fixed roll you assume, plus the Constitution modifier again. The rules guarantee a minimum of 1 hit point gained per level, even with a very negative modifier.
| Term | Meaning |
|---|---|
| Hit die | The die size set by class: d6 for Sorcerer and Wizard, d8 for Bard, Cleric, Druid, Monk, Rogue and Warlock, d10 for Fighter, Paladin and Ranger, d12 for Barbarian. |
| Constitution modifier | The ability modifier derived from a character’s Constitution score, added to HP at every level, not just the first. |
| Average hit die value | The hit die’s mean roll, rounded up: half the die size plus one, for example 6 for a d10. |
The inputs explained
| Field | What to enter |
|---|---|
| Class hit die | The class hit die, which sets both the starting HP and the average gain per level. |
| Character level | Character level, from 1 to 20. |
| Constitution modifier | Constitution modifier, applied at every level including the first. Can be negative. |
| HP gained per level after 1st | Whether to use the standard average value each level or a fixed roll you assume instead. |
| Assumed roll per level (if using a fixed roll) | Only used when the method above is set to a fixed roll; must be between 1 and the hit die size. |
When to use it
Building a character before the first session
Working out expected HP at 1st level, and how it grows, helps set expectations before a new character sees combat, especially when comparing hit die classes against each other.
Planning ahead for a multiclass or high-level build
HP at a future level is useful to know in advance, whether checking how tough a level 10 or level 15 version of a character will be, or comparing two hit die choices before committing to a class.
Using average HP instead of rolling
Many tables use the fixed average value per level rather than rolling, to avoid unlucky HP totals; this calculator reproduces that standard method exactly, or lets a specific fixed roll be tested instead.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How HP grows with level for a d10 hit die and a +2 Constitution modifier
A d10 class such as a Fighter, at a +2 Constitution modifier, across a range of levels.
How HP at level 5 changes with hit die size
The same level 5 character and +2 Constitution modifier, across each hit die size.
Questions
Does this use 5th-edition rules specifically?
Yes. This follows the hit point rules published in the 5th-edition System Reference Document. Earlier editions and homebrew variants calculate HP differently, so check which ruleset a table is using before relying on this for another edition.
Should I use average HP or roll for it?
Both are valid under the rules; it is a table preference. Rolling gives more variance and the chance of an unusually tough or fragile character, while the average method gives a predictable, steady progression. This calculator supports either.
Why is there a minimum of 1 HP gained per level?
The rules guarantee at least 1 hit point per level even if a very low Constitution modifier would otherwise push the gain to zero or below, so a character’s HP total can never shrink as they level up.
Does Constitution modifier change if my score changes later?
Yes, and 5e recalculates retroactively: if an ability score increase raises the Constitution modifier, the character gains HP for every level already taken, not just future ones, since the modifier is applied at every level.
For the odds behind a roll rather than the hit points it produces, see the probability of events calculator.