Calculator
Enter a dice expression like 2d6+4 or 1d8+1d6+3 to get average, min/max, and expected damage per round.
Supports + and - terms. Examples: 1d12+5, 2d6+1d8+4, 4d6-2.
What this D&D dice average calculator does
This tool estimates average damage from any standard dice expression. It also computes expected damage per attack and per round when you add hit chance, critical chance, and number of attacks.
That makes it useful for quick comparisons between weapons, spells, and builds. Instead of rolling hundreds of test dice, you can model outcomes in seconds.
How average dice math works
For a single die with N sides, the average is:
(N + 1) / 2
So:
- d4 average = 2.5
- d6 average = 3.5
- d8 average = 4.5
- d10 average = 5.5
- d12 average = 6.5
- d20 average = 10.5
For multiple dice, multiply by the number of dice. Example: 2d6 = 2 × 3.5 = 7. Then add any flat modifier. So 2d6+4 has an average of 11.
Quick reference: expected damage formula
- Average on hit = dice average + flat modifier
- Average on crit = (dice average × crit multiplier) + flat modifier
- Expected per attack = (non-crit hit chance × avg hit) + (crit chance × avg crit)
- Expected per round = expected per attack × attacks per round
Using the calculator for build decisions
1) Compare weapon choices
Try the same hit chance with two expressions, like 1d8+3 versus 2d6+1. You can quickly see which option
gives better long-run damage.
2) Evaluate spell slots
Spells with many dice (like 8d6) have high average output but wide spread. The min/max view helps you judge
both consistency and upside.
3) Estimate DPR with extra attacks
Set attacks per round to 2, 3, or more to model martial scaling at higher levels. This gives a more realistic baseline than raw “damage on hit.”
Examples
- 1d8+3 average on hit: 7.5
- 2d6+4 average on hit: 11
- 8d6 average on hit: 28
- 1d10+4 average on hit: 9.5
If you include crits at 5% and use a x2 dice multiplier, expected output rises slightly because crits add extra dice value.
Common mistakes this tool helps avoid
- Forgetting that modifiers are usually not doubled on crits
- Comparing builds only by maximum damage instead of expected value
- Ignoring hit rate when estimating real combat performance
- Underestimating the difference between one big hit and multiple attacks
FAQ
Does this support multiple dice terms?
Yes. Expressions like 1d8+1d6+4 are fully supported.
Can I subtract values?
Yes. You can enter terms like 2d6+5-2 or 3d8-1d4+4.
Is this only for D&D 5e/2024?
The math works for any d20-style tabletop RPG that uses standard dice notation.