combat calculator 5e

How to Use This Combat Calculator 5e Tool

This calculator is built to answer one practical question: how much damage should I expect to deal each round? You provide your attack bonus, your target’s AC, your damage dice, and your number of attacks. The tool then calculates expected DPR (damage per round), including critical hits.

Unlike a single dice roll, expected damage is about probabilities over many attacks. If your fighter swings with +7 to hit against AC 16, your odds are predictable over time, even though each individual attack still depends on luck.

Inputs Explained

• Attack Bonus: your d20 modifier to hit (proficiency + ability modifier + magic bonuses).
• Target AC: the enemy armor class you are trying to hit.
• Roll Type: normal, advantage, or disadvantage.
• Critical Range: usually 20, but features like Champion Fighter can expand this to 19–20.
• Damage Dice Expression: supports expressions like 1d8, 2d6+1d4, or 1d10+2.
• Flat Damage Bonus: extra static damage (ability modifier, magic weapon bonus, etc.).
• Attacks per Round: total attack attempts in a typical round.
• Target HP (optional): estimates rounds to defeat based on average DPR.

The Math Behind the Calculator

Hit Chance in 5e

In 5e, a natural 1 misses and a natural 20 hits automatically (and crits). For all other rolls, the calculator checks whether:

d20 + attack bonus ≥ target AC

When advantage or disadvantage is selected, it evaluates the higher or lower die exactly (not approximately), which gives more accurate results than rough estimates.

Critical Damage

On a crit, damage dice are doubled while flat modifiers are not. If your normal damage is 1d8 + 4, your crit is effectively 2d8 + 4. The calculator applies this rule directly when computing expected damage.

Expected DPR Formula

Expected damage per attack is:

(non-crit hit chance × average normal damage) + (crit chance × average crit damage)

Then it multiplies by attacks per round to give expected DPR.

Practical Optimization Tips

• Advantage is huge: it boosts both hit chance and crit chance at once.
• Don’t ignore attack bonus: +1 to hit can outperform +1 damage depending on AC.
• Expanded crit range scales best with many attacks: more swings means more opportunities to crit.
• Use this for comparisons: test fighting styles, feats, and weapon choices with the same target AC.

Important Limits of Any DPR Calculator

Even a strong combat calculator cannot model everything in a real encounter. It does not automatically include positioning, concentration failures, conditions, saving throw spells, resistance/vulnerability, or party synergy. Use expected DPR as a planning baseline, then adjust for real table dynamics.

Quick Example

Try this setup: attack bonus +7, AC 16, normal roll, crit on 20, damage 1d8, flat +4, and 2 attacks. Then switch to advantage and compare the result. You’ll see exactly why reliable advantage effects can dramatically increase total encounter output.

Final Thoughts

If you want fast, repeatable comparisons for martials, summoned attackers, or even homebrew balance checks, this combat calculator 5e page is a practical tool. Run multiple scenarios, compare AC bands, and optimize your action economy with real probability instead of guesswork.