5e calculator - Aaron Graves, PhDude Replica

D&D 5e Combat & Stat Calculator

Quickly compute ability modifiers, proficiency bonus, attack bonus, hit chance, spell save DC, and passive perception.

Character Level (1-20)

Target Armor Class (AC)

Attack Ability Score (STR/DEX/etc.)

Proficient with this attack

Roll Mode

Magic/Item Bonus to Attack

Other Attack Bonus

Damage Dice (e.g., 1d8, 2d6)

Flat Damage Bonus

Spellcasting Ability Score

Other Spell Save DC Bonus

Wisdom Score (for Passive Perception)

Perception Proficiency

Other Passive Perception Bonus

Enter your values and click Calculate 5e Stats.

What this 5e calculator does

This 5e calculator is designed for fast table use and character planning. It combines the most common D&D 5e math into one place: ability modifiers, proficiency bonus by level, attack bonus, chance to hit a target AC, critical hit chance, spell save DC, and passive perception.

Instead of bouncing between notes and rulebooks, you can test a build in seconds. Change level, switch from normal rolls to advantage, or tweak damage dice and immediately see the impact.

Core formulas used in this tool

Ability modifier

Ability modifier is calculated with the standard rule: floor((ability score - 10) / 2). For example, 16 gives +3, 14 gives +2, and 8 gives -1.

Proficiency bonus by level

Levels 1-4: +2
Levels 5-8: +3
Levels 9-12: +4
Levels 13-16: +5
Levels 17-20: +6

Attack bonus and hit chance

Attack bonus includes your attack ability modifier, proficiency (if applicable), magic bonus, and other modifiers. Hit chance respects the 5e core rule that a natural 1 always misses and a natural 20 always hits. Advantage and disadvantage are calculated by evaluating two d20 rolls and selecting the higher or lower result.

Expected damage per attack

Provide a dice expression such as 1d8 or 2d6 plus flat bonus damage. The calculator estimates expected damage by combining:

Non-critical hit probability × average normal hit damage
Critical hit probability × average critical damage (double dice, same flat bonus)

Spell save DC and passive perception

Spell save DC is computed as 8 + proficiency + spellcasting ability modifier + other bonuses. Passive perception is 10 + Wisdom modifier + proficiency/expertise + other bonuses.

Practical example

Suppose a level 5 character has 16 Strength, proficiency with a +1 weapon, and attacks AC 15 with a longsword (1d8 + 3 damage). This tool quickly shows your attack bonus, hit chance, critical chance, and estimated damage per swing. Change the roll mode to advantage and you can immediately see how much your expected damage rises.

Tips for faster sessions

Preload your most common attack setup before combat starts.
Save baseline values for normal, advantage, and disadvantage scenarios.
Use expected damage as a planning metric, not a guarantee for any single round.
For unusual features (rerolls, expanded crit range, smites), treat this as a baseline and adjust manually.

FAQ

Does this support all homebrew rules?

Not directly. This calculator follows standard 5e math. Homebrew mechanics can often be represented by adding custom bonuses where appropriate.

Can I enter negative modifiers?

Yes. Inputs allow negative values where they make sense, useful for penalties, curses, or situational effects.

What dice formats are accepted?

Use simple expressions like 1d4, 1d10, 2d6, or 4d8. If the format is invalid, the tool still calculates other outputs and flags the damage input.