bg3 calculator

What this BG3 calculator does

This BG3 calculator is a fast way to estimate your expected combat output in Baldur’s Gate 3. Instead of guessing whether a setup is good, you can compare builds with actual probabilities. Enter your attack bonus, target AC, damage dice, and number of attacks. The tool returns:

• Chance to hit
• Chance to crit
• Chance to miss
• Expected damage per attack
• Expected damage per round (DPR)

It supports normal rolls, advantage, and disadvantage, plus expanded critical thresholds for features that crit on values lower than 20.

How to use it

1) Set your attack profile

Enter your total attack bonus exactly as it appears in combat. This usually includes proficiency bonus, ability modifier, weapon bonuses, and temporary buffs.

2) Set target AC

Choose the enemy Armor Class you want to test against. If you are planning for a whole area, run multiple AC values (for example 14, 16, and 18) to understand how your build scales.

3) Enter damage expression

Use standard dice notation like 1d8+4, 2d6+5, or 1d10+1d4+6. Flat values are allowed, and multiple dice groups work.

4) Add crit-only bonus (optional)

If your setup adds extra damage only on a critical hit, enter it in the crit-only field. If not, leave it blank.

Combat math, simplified

The calculator uses exact d20 outcome distributions. For advantage and disadvantage, it evaluates all two-die combinations, then applies BG3-style attack logic:

• Natural 1 always misses
• Natural 20 always hits and crits
• Other rolls must meet or exceed AC after modifiers
• Critical threshold can be customized (for example, 19–20)

It then combines hit probability with average damage to produce expected values. This helps compare “high accuracy, lower damage” versus “high damage, lower accuracy” options.

Practical build comparisons you can test

Great Weapon vs. Sword-and-Board

Try one profile with heavier dice and lower hit chance, then compare to a more accurate setup. Against high AC targets, accuracy often wins.

Advantage-heavy setups

If your party regularly generates advantage (positioning, crowd control, conditions), toggle advantage and watch crit chance jump dramatically.

Multi-attack scaling

Increase attacks per round to model extra attack features, off-hand strikes, or action economy spikes. Small per-attack gains become large over a full round.

Tips for better BG3 damage planning

• Run at least 3 enemy AC values before deciding between two items.
• Compare normal and advantage modes; many builds are condition-dependent.
• Track how often your buffs are active in real encounters.
• Use expected DPR as a guide, not a guarantee for any single turn.

Limitations to keep in mind

This calculator focuses on direct attack-roll damage. It does not model every BG3 mechanic, such as saving throw spells, resistances, vulnerabilities, on-kill effects, terrain interactions, or resource constraints over long adventuring days. Use it as a clean baseline for decision-making.

Bottom line

A good BG3 calculator turns build planning from guesswork into strategy. Use this page to test gear changes, feat choices, and party support conditions in seconds. If two options feel close, the numbers usually reveal the stronger one for your target scenario.