Diceplots

Concepts → When crit chance beats base damage

When +5% crit chance beats +1 damage — and when it doesn't

Build guides almost always optimise for expected DPR (damage per round). That number alone misses the question that actually matters at the table or in the dungeon: which build kills this specific target in fewer rounds? The answer depends on where the target's HP sits relative to your average swing.

The setup

Take a baseline 5e weapon swing of 2d6+5 — a greatsword with a +5 strength modifier, level-5 fighter. On a normal hit it deals 7–17 damage with mean 12. On a critical hit (5e doubles the dice) it becomes 4d6+5: 9–29 damage, mean 19.

Two ways to make this swing better:

  • +1 damage modifier (e.g. a +1 weapon, or a magical buff). Every swing now does 2d6+6; on a crit 4d6+6. Mean per swing including the standard 5% crit chance: 13.35.
  • +5% crit chance (e.g. Champion fighter at level 3 extending the crit range from 20-only to 19–20). Damage rolls stay 2d6+5 normal / 4d6+5 crit, but crit probability rises from 5% to 10%. Mean per swing: 12.7.

On expected DPR alone, +1 damage wins by 0.65 per swing — about 5% more output per round. Most build guides stop there. But the distributions tell a richer story.

Distribution shapes on a normal hit vs a crit

The base swing tops out at 17. The crit swing tops out at 29 and is much wider. Visually:

2d6+5
min 7 max 17 mean 12.00 12
P(finish at 17 HP) = 2.78% (1/36)
  • 7 2.78%
  • 8 5.56%
  • 9 8.33%
  • 10 11.11%
  • 11 13.89%
  • 12 16.67%
  • 13 13.89%
  • 14 11.11%
  • 15 8.33%
  • 16 5.56%
  • 17 2.78%
4d6+5
min 9 max 29 mean 19.00 19
P(finish at 17 HP) = 76.08% (493/648)
  • 9 0.08%
  • 10 0.31%
  • 11 0.77%
  • 12 1.54%
  • 13 2.70%
  • 14 4.32%
  • 15 6.17%
  • 16 8.02%
  • 17 9.65%
  • 18 10.80%
  • 19 11.27%
  • 20 10.80%
  • 21 9.65%
  • 22 8.02%
  • 23 6.17%
  • 24 4.32%
  • 25 2.70%
  • 26 1.54%
  • 27 0.77%
  • 28 0.31%
  • 29 0.08%

The kill-probability angle

Consider three target HP values. For each, work out the per-swing probability of finishing the target — combining the kill probability on a normal roll (95% or 90% of the time, depending on crit range) with the kill probability on a crit (5% or 10%).

Drag the HP. +1 damage wins for the bulk of plausible targets; +5% crit wins in the narrow band between the normal-roll max and the crit-roll max where only crits can land the kill.

At 12 HP, +1 damage wins: 73.59% vs +5% crit's 62.38% (Δ = 11.21%).

Build Per-swing damage P(kill at 12 HP)
+1 damage 2d6+6 normal, 4d6+6 crit (5%) 73.59%
+5% crit 2d6+5 normal, 4d6+5 crit (10%) 62.38%

+1 damage wins for the bulk of plausible targets — the modifier shifts every swing's distribution upward, and that's a strict win whenever your normal-roll output is anywhere near the threshold. +5% crit wins in a narrow band: HP roughly 18–26, where the target sits above your normal-roll maximum but below your crit-roll maximum. In that zone, only the crit branch can land the kill, and you've doubled how often it fires.

At the extreme upper end (HP near the crit max) +1 damage wins again, because at that point both builds are vanishingly likely to crit-kill and the +1 modifier is what tips the very rare crits over the line.

The intuition

Crit chance is variance-on-tap. Each percentage point of crit chance moves a sliver of probability from the normal-roll distribution to the crit-roll distribution — and the crit distribution has a much higher max. If your normal-roll max is already enough to one-shot anything you're fighting, that probability shift is wasted (you'd have killed the target on the cheaper normal roll anyway). If your normal-roll max isn't enough, every percentage point of crit chance directly buys you kills you couldn't otherwise land.

Stated as a rule: crit chance is worth more in the band of HPs between your normal-roll maximum and your crit-roll maximum — the "only crits can do this" zone. Below your normal max, raw damage modifiers win because they shift every swing upward. Above your crit max, neither build can reach the target anyway. The crit-wins zone is the narrow gap in the middle.

Where this matters in practice

  • Baldur's Gate 3 Champion fighter (extended crit range) shines specifically against high-HP solo bosses where normal hits chip but rarely close out. Against a swarm of low-HP enemies, +1 damage / +1 to-hit wins easily.
  • Diablo 4 / Path of Exile / Last Epoch "should I stack crit chance or +damage" — same question, same answer. Crit-stacking pays off most against rare/elite/boss enemies whose HP sits well above your normal-hit damage. Against trash mobs you'd already one-shot, +damage is wasted on overkill but crit-chance is wasted even harder.
  • Multi-attack builds — the question changes shape because each individual swing has a smaller chance of needing to land the kill alone. Multiple attacks per round push the relevant per-swing damage threshold downward, which moves the +damage / +crit crossover correspondingly.

Try it yourself

↦ /vs/2d6+5/4d6+5 — normal vs crit-doubled side by side ↦ /strike/2d6+5 — full distribution of one swing ↦ /strike/4d6+5 — full distribution of a crit swing