D&D Damage Calculator Guide: DPR, Critical Hits & Combat Math

The DPR Formula Explained

Damage Per Round (DPR) is the single most useful metric for comparing combat effectiveness in D&D 5e. It tells you how much damage a character deals on an average turn, accounting for hit probability.

The basic formula is:

DPR = (Hit Chance × Average Damage) + (Crit Chance × Extra Crit Damage)

To calculate hit chance: you need to roll (target AC – attack bonus) or higher on a d20. Against AC 15 with a +7 bonus, you need an 8+, giving you a 65% hit chance (13 out of 20 results succeed). Remember that a natural 1 always misses and a natural 20 always hits.

Worked Example: Level 5 Fighter

A 5th-level Fighter with 18 Strength, a greatsword (2d6), and two attacks via Extra Attack:

• Attack bonus: +4 (STR) + 3 (proficiency) = +7
• Damage per hit: 2d6 + 4 = 11 average
• Crit bonus damage: 2d6 = 7 average
• Hit chance vs AC 15: (20 – 8 + 1)/20 = 65%
• Crit chance: 5% (natural 20)

DPR per attack = (0.65 × 11) + (0.05 × 7) = 7.15 + 0.35 = 7.5
Total DPR with 2 attacks = 15.0

With Great Weapon Fighting style (reroll 1s and 2s on damage dice), average greatsword damage rises from 7 to 8.33, boosting total DPR to roughly 17.2.

Critical Hit Math

On a critical hit, you double all damage dice but not your ability modifier. This distinction matters:

Weapons with more damage dice benefit more from crits. The greataxe (1d12) has a higher single-die max (12) but the greatsword (2d6) gets more bonus crit damage on average. This is why Half-Orc Barbarians favor greataxes— their Savage Attacks trait adds one extra weapon die on a crit, and 1d12 > 1d6 for that bonus.

Saving Throw Damage

Many spells and abilities force a saving throw instead of making an attack roll. The damage calculation differs:

• No critical hits are possible on saving throw damage
• Most save-based damage deals half damage on a successful save
• Save DC = 8 + proficiency + spellcasting modifier

For a Fireball (8d6, DC 15 DEX save) against a target with +3 DEX save:

• Target needs to roll 12+ to save: 45% save chance
• Average damage: 28 (full) or 14 (half)
• Expected damage = (0.55 × 28) + (0.45 × 14) = 15.4 + 6.3 = 21.7

The “half on save” mechanic means save-based spells have a higher damage floor than attack roll spells — you always deal somedamage. Against multiple targets, Fireball's expected damage multiplies by each creature in the 20-foot radius sphere, making it one of the most efficient damage spells in the game per spell slot.

Great Weapon Master and Sharpshooter Math

Both feats offer the same trade-off: –5 to hit, +10 damage. Whether this trade is worthwhile depends entirely on your hit chance before the penalty.

The breakeven point is roughly when your base hit chance is around 60%. Below that, the –5 penalty costs more damage than the +10 gains. With advantage, the effective hit chance jumps by 20–25 points, making GWM/Sharpshooter profitable against almost any AC. This is why Barbarian's Reckless Attack (free advantage on STR attacks) pairs so well with GWM.

Advantage and Disadvantage

Advantage (roll 2d20, take higher) and disadvantage (roll 2d20, take lower) are among the most impactful mechanics in 5e combat. The exact bonus depends on the target number:

Advantage is most powerful when you need an 11 on the die, providing an effective +5 bonus. It also doubles your crit chance from 5% to 9.75%, since you now have two chances to roll a natural 20.

DPR Benchmarks by Level

Based on analysis from the D&D 5e community and optimizer forums, here are approximate “good” sustained DPR benchmarks for martial characters (no limited-use resources):

These numbers assume fighting a monster whose CR equals the party level, with standard magic items for that tier. Casters typically deal lower sustained DPR but spike higher with spell slots, and they bring control and AoE that raw DPR doesn't capture.

Common DPR Calculation Mistakes

Forgetting to Factor Hit Chance

Saying “my character deals 2d6+14 damage per hit” is meaningless without accounting for hit probability. A +14 damage build that only hits 30% of the time deals less DPR than a +4 damage build that hits 75%. Always multiply by hit chance.

Counting Action Surge Every Round

Action Surge is once per short rest, not once per round. Including it in your “sustained DPR” calculation inflates the number. Calculate your base DPR first, then note burst potential separately.

Ignoring Resistance and Immunity

According to the 2024 Monster Manual, roughly 40% of monsters have resistance to at least one damage type, and about 15% have immunity. Fire resistance is the most common, affecting over 60 monster stat blocks. Account for this when evaluating fire-based damage builds.

Comparing Single-Target to AoE

A Fireball that hits 4 creatures deals an expected 86.8 total damage from one 3rd-level slot. Comparing that to a single-target attack's 15 DPR is apples to oranges. Evaluate AoE spells based on the typical number of targets in your campaign's encounters.

Not Accounting for Bonus Action Economy

Monks, dual-wielders, and certain builds depend on bonus action attacks for their DPR. If your bonus action is already committed to a spell like Hex or Spiritual Weapon, you cannot also use it for an off-hand attack. Track your action economy across all three action types.

Frequently Asked Questions

How do you calculate damage per round (DPR) in D&D 5e?

DPR = (hit chance × average damage on hit) + (crit chance × extra crit damage). For a Fighter with +7 to hit against AC 15, the chance to hit is 65% (need 8+ on d20). If dealing 2d6+5 (average 12) damage, DPR = 0.65 × 12 + 0.05 × 7 = 8.15 per attack. Multiply by number of attacks per round for total DPR.

How do critical hits work in D&D 5e?

A natural 20 on an attack roll is a critical hit. You roll all damage dice twice (but only add the modifier once). A greatsword attack dealing 2d6+4 would deal 4d6+4 on a critical hit, averaging 18 instead of 11. Champion Fighters crit on 19–20, doubling their crit chance to 10%.

Is Great Weapon Master worth the –5 penalty in D&D 5e?

Against AC 15 or lower with a +7 or higher attack bonus, GWM's –5/+10 trade is almost always a net DPR increase. Against AC 18+, the penalty reduces your hit chance below 50%, making it a net loss without advantage. With advantage, GWM is profitable against virtually any AC you'll encounter.

How does advantage affect damage output in D&D 5e?

Advantage lets you roll two d20s and take the higher result. On average, this adds roughly +3.3 to +5 to your effective roll depending on the target number. Against AC 15 with a +5 bonus, advantage raises your hit chance from 55% to roughly 80%, increasing DPR by about 45%.

What is the highest damage build in D&D 5e?

For nova damage (single-round burst), Paladin/Sorcerer multiclass builds using Divine Smite on critical hits can deal 100+ damage in one round. For sustained DPR, level 20 Fighters with Action Surge average 60–80+ DPR depending on subclass and magic weapons. Optimized Gloom Stalker Ranger/Fighter multiclass builds are also top contenders for sustained output.