Pathfinder 2e Combat Calculator

Calculate attack rolls, damage, criticals, and more for your Pathfinder 2nd Edition encounters.

Combat Encounter Tool

What is a Pathfinder 2e Combat Calculator?

A Pathfinder 2e combat calculator is an indispensable tool for players and Game Masters (GMs) navigating the tactical depths of the Pathfinder Second Edition role-playing game. It streamlines the often complex and time-consuming process of determining the success of attacks, the amount of damage dealt, and the probability of critical hits. By inputting key combat statistics like attack bonuses, target Armor Class (AC), and weapon damage, this calculator provides instant, accurate results, allowing participants to focus on the narrative and strategic elements of the game rather than manual calculations. This tool is particularly useful for managing multiple enemies, calculating complex attack sequences, and understanding the statistical probabilities behind combat outcomes.

Who should use it?

Any participant in a Pathfinder 2e game can benefit from a Pathfinder 2e combat calculator:

• Players: To quickly assess their chances of hitting, understand their damage output, and plan their actions effectively.
• Game Masters (GMs): To efficiently manage monster attacks, quickly determine hit or miss for NPCs, and ensure balanced encounter difficulty.
• New Players: To grasp the fundamental mechanics of attack rolls and damage in PF2e without being overwhelmed by math.
• Experienced Players: To optimize character builds, fine-tune equipment choices, and explore theoretical damage per round (DPR) scenarios.

Common Misconceptions:

A frequent misconception is that these calculators are only for min-maxing or overly complex character optimization. In reality, a Pathfinder 2e combat calculator is a practical tool for clarity and speed, making the game more accessible and enjoyable for everyone. Another misconception is that it removes the element of chance; while it quantifies probabilities, the dice still hold sway in actual gameplay, and the calculator helps contextualize those rolls.

Understanding the intricacies of combat in Pathfinder 2e, especially attack rolls and damage calculation, is crucial for an enjoyable experience. Our Pathfinder 2e combat calculator is designed to simplify this process.

Pathfinder 2e Combat Calculator Formula and Mathematical Explanation

The core of the Pathfinder 2e combat calculator revolves around the attack roll mechanic and subsequent damage calculation. Here’s a breakdown of the formulas used:

Attack Roll and Hit Chance

The fundamental check is: Roll + Attack Bonus vs. Target AC.
The calculator determines the probability of hitting by examining the possible results of a single d20 roll (1 through 20).

Let:

• RB = Roll Bonus (Attack Bonus)
• AC = Target Armor Class

The minimum roll needed to hit is AC - RB.
However, PF2e has specific critical success and failure rules:

• Critical Success (Crit): Natural roll is 10 or more *above* the roll needed to hit.
• Success (Hit): Natural roll meets or beats the roll needed to hit, but is less than 10 above.
• Failure: Natural roll is less than the roll needed to hit.
• Critical Failure (Crit Fail): Natural roll is 10 or more *below* the roll needed to hit. (Or a natural 1).

The calculator simplifies this by focusing on the chance to hit, critical hit, and miss.

Hit Roll Threshold: Needed_Roll = AC - RB

A natural roll of 1 always results in a critical failure.
A natural roll of 20 always results in a critical success.

Hit Chance Calculation (for rolls other than 1 or 20):

If Needed_Roll is 1 or less, you automatically succeed (unless it’s a natural 1).
If Needed_Roll is 21 or more, you automatically fail (unless it’s a natural 20).
Otherwise, the number of successful outcomes is 21 - Needed_Roll.
The probability of hitting is then (Number of successful outcomes) / 20.

Critical Hit Chance Calculation:

A critical hit occurs if the natural roll is 10 or more above the Needed_Roll, or if a natural 20 is rolled and it still hits.

The threshold for a critical hit (before considering natural 1/20 rules) is Crit_Needed_Roll = AC - RB - 10.

The number of critical hit outcomes (excluding natural 20) is 21 - Crit_Needed_Roll.

The total critical hit chance is effectively the chance to roll Needed_Roll + 10 or higher, capped by the natural 20.

A simpler way for the calculator: If the natural roll is 20, it’s a crit. If the natural roll is 10 or more above the minimum needed to hit, it’s a crit.
So, the number of critical hit outcomes is effectively max(0, 20 - max(1, Needed_Roll + 10) + 1), plus the guaranteed crit on a natural 20 if it succeeds.
The calculator determines the number of rolls from 1-20 that satisfy the conditions.

Damage Calculation

Let:

• DDS = Damage Die Size (e.g., 4 for d4, 6 for d6)
• DDN = Damage Die Number (number of dice)
• DB = Additional Damage Bonus
• CM = Critical Hit Multiplier

Average Damage Die Roll: (DDS + 1) / 2

Average Damage Per Hit (assuming a hit):
( (DDN * (DDS + 1) / 2) + DB )

Average Damage Per Critical Hit:
( (DDN * (DDS + 1) / 2 * CM) + DB )

Average Damage Per Attack (overall):
This accounts for misses, hits, and critical hits.

Let:

• P_Hit = Probability of a normal hit
• P_Crit = Probability of a critical hit
• P_Miss = Probability of a miss

Avg_Damage_Per_Attack = (P_Crit * Avg_Damage_Per_Critical_Hit) + (P_Hit * Avg_Damage_Per_Hit) + (P_Miss * 0)

Note: This calculation simplifies the critical success/failure conditions based on the roll. A natural 20 always crits if it hits. Rolling 10+ above the needed roll is a crit. Rolling 10+ below the needed roll is a crit fail. A natural 1 is always a crit fail.

Variables Table

Key Variables in Pathfinder 2e Combat Calculations

Variable	Meaning	Unit	Typical Range
Attack Bonus (RB)	The sum of proficiency bonus, attribute modifier, item bonuses, and circumstance/status bonuses that apply to an attack roll.	Modifier	-2 to +30+
Target Armor Class (AC)	The defensive value of the target that must be met or exceeded by an attack roll to land a hit.	Value	10 to 50+
Damage Die Number (DDN)	The quantity of dice rolled for the weapon’s base damage.	Count	1 to 4+
Damage Die Size (DDS)	The number of sides on the dice used for the weapon’s base damage (e.g., 4 for d4, 6 for d6).	Sides	4, 6, 8, 10, 12
Additional Damage (DB)	Flat bonus damage from sources like attribute modifiers, weapon potency runes, or class features.	Damage Value	0 to 15+
Critical Multiplier (CM)	The factor by which the damage dice are multiplied on a critical hit (standard is 2).	Factor	2 (standard), 3 (e.g., for flaming/frost daggers)
Number of Attacks (NA)	The total number of attacks made in a single action or turn.	Count	1 to 4+

Practical Examples (Real-World Use Cases)

Example 1: Standard Melee Attack

A level 5 fighter with a Scimitar (1d6 slashing, +8 attack bonus, +3 additional damage) attacks a Goblin Guard (AC 17). The fighter makes one attack.

Inputs:

• Attack Bonus: 8
• Target AC: 17
• Damage Dice Number: 1
• Damage Die Size: 6 (d6)
• Additional Damage: 3
• Critical Multiplier: 2
• Number of Attacks: 1

Calculation Breakdown:

• Needed Roll to Hit: 17 (AC) – 8 (Attack Bonus) = 9
• Needed Roll for Crit: 9 + 10 = 19
• Possible Rolls: 1-20
• Rolls to Crit: 19, 20 (2 outcomes)
• Rolls to Hit (Success): 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 (10 outcomes)
• Rolls to Miss: 1, 2, 3, 4, 5, 6, 7, 8 (8 outcomes)
• Hit Chance: 10/20 = 50% (excluding natural 1/20 special cases for simplicity in this explanation, actual calculator handles edge cases)
• Crit Chance: 2/20 = 10% (rolls 19, 20 if they succeed)
• Miss Chance: 8/20 = 40%
• Avg Damage Per Hit: (1 * (6+1)/2) + 3 = 3.5 + 3 = 6.5
• Avg Damage Per Crit: (1 * (6+1)/2 * 2) + 3 = (3.5 * 2) + 3 = 7 + 3 = 10
• Avg Damage Per Attack: (0.10 * 10) + (0.50 * 6.5) + (0.40 * 0) = 1 + 3.25 + 0 = 4.25

Calculator Output (Approximate):

• Hit Chance: 55% (50% success + 5% chance of nat 20 succeeding)
• Crit Hit Chance: 10% (chance of rolling 19 or 20)
• Avg Damage Per Hit: 6.5
• Avg Damage Per Attack: 4.25
• Primary Result (Hit Chance): 55%

Interpretation: The fighter has a decent chance to hit the Goblin Guard. On average, each attack will deal about 4.25 damage, with critical hits dealing around 10 damage. The fighter is likely to hit more often than miss.

Example 2: Ranged Attack with Opportunity

A level 8 Ranger with a Longbow (+12 attack bonus, 1d8 piercing, +2 additional damage) attacks a distant Orc Shaman (AC 22). The Ranger performs a Stride + Shoot maneuver, making two attacks. Assume standard crit multiplier and no range penalties for simplicity.

Inputs:

• Attack Bonus: 12
• Target AC: 22
• Damage Dice Number: 1
• Damage Die Size: 8 (d8)
• Additional Damage: 2
• Critical Multiplier: 2
• Number of Attacks: 2

Calculation Breakdown:

• Needed Roll to Hit: 22 (AC) – 12 (Attack Bonus) = 10
• Needed Roll for Crit: 10 + 10 = 20
• Possible Rolls: 1-20
• Rolls to Crit: 20 (1 outcome)
• Rolls to Hit (Success): 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 (10 outcomes)
• Rolls to Miss: 1, 2, 3, 4, 5, 6, 7, 8, 9 (9 outcomes)
• Hit Chance (per attack): 10/20 = 50% (excluding nat 1/20)
• Crit Chance (per attack): 1/20 = 5% (only natural 20)
• Miss Chance (per attack): 9/20 = 45%
• Avg Damage Per Hit: (1 * (8+1)/2) + 2 = 4.5 + 2 = 6.5
• Avg Damage Per Crit: (1 * (8+1)/2 * 2) + 2 = (4.5 * 2) + 2 = 9 + 2 = 11
• Avg Damage Per Attack: (0.05 * 11) + (0.50 * 6.5) + (0.45 * 0) = 0.55 + 3.25 + 0 = 3.8
• Total Avg Damage (2 attacks): 2 * 3.8 = 7.6

Calculator Output (Approximate):

• Hit Chance: 55% (50% success + 5% chance of nat 20 succeeding)
• Crit Hit Chance: 5% (chance of rolling 20)
• Avg Damage Per Hit: 6.5
• Avg Damage Per Attack: 3.8
• Primary Result (Hit Chance across 2 attacks): ~75% (cumulative chance to hit at least once)

Interpretation: The Ranger has a 55% chance to hit on each attack against the Orc Shaman. This means with two attacks, the cumulative chance of hitting at least once is quite high (~75%). Each attack, on average, deals 3.8 damage. This informs the Ranger about their effectiveness in this specific encounter.

How to Use This Pathfinder 2e Combat Calculator

1. Input Your Character/Monster Stats:
   • Attack Bonus: Enter your character’s or monster’s total attack bonus for the weapon or strike being used. This includes proficiency, relevant ability modifiers, and item bonuses.
   • Target Armor Class (AC): Input the AC of the creature you are attacking.
   • Damage Dice Number & Size: Specify the number and type (e.g., 1d8) of damage dice for your weapon or strike.
   • Additional Damage: Add any flat bonus damage (e.g., from Strength modifier, potency runes, or specific abilities).
   • Critical Multiplier: Most weapons have a multiplier of 2. Some special weapons might have 3.
   • Number of Attacks: If your action allows for multiple attacks (like the Flurry of Blows monk ability or standard actions for higher levels), enter the total number of attacks.
2. Initiate Calculation: Click the “Calculate Combat” button.
3. Read the Results:
   • Primary Result (Hit Chance): This is the overall percentage chance that at least one of your attacks will hit the target across all attacks made. A higher percentage indicates greater reliability.
   • Critical Hit Chance: The percentage chance that any single attack roll will result in a critical hit.
   • Avg Damage Per Hit: The average damage dealt by a single attack, assuming it successfully hits (not including critical hits).
   • Avg Damage Per Attack: The average damage dealt by a single attack, factoring in the chance of misses, hits, and critical hits. This is often the most realistic measure of sustained damage output.
   • Formula Explanation: Provides a brief overview of how the results were derived.
4. Make Decisions: Use the results to inform your tactical choices. If your hit chance is low, consider using actions that debuff the enemy’s AC, gain status bonuses to your attack, or target a different enemy. If your average damage is low, explore ways to increase your damage dice, add flat damage bonuses, or utilize critical hit opportunities.
5. Reset or Copy:
   • Click “Reset” to clear all fields and return to default values for a fresh calculation.
   • Click “Copy Results” to copy the main result, intermediate values, and key assumptions to your clipboard for use elsewhere.

This Pathfinder 2e combat calculator is a powerful tool for understanding combat probabilities and optimizing your character’s effectiveness in battle.

Key Factors That Affect Pathfinder 2e Combat Results

Several elements significantly influence the outcomes generated by a Pathfinder 2e combat calculator and, more importantly, the actual combat in the game. Understanding these factors is key to effective strategy and character building.

• Attack Bonus vs. Target AC: This is the most direct factor. A higher attack bonus relative to the target’s AC dramatically increases the hit chance. Conversely, facing high-AC enemies requires maximizing your attack bonus or accepting a lower hit probability. This is fundamental to Pathfinder 2e encounter design.
• Enemy Defenses (AC, Fortitude, Reflex, Will): While the calculator focuses on AC, other defenses play a role. Spells and abilities often target Fortitude, Reflex, or Will saves. A character might have a high attack bonus but struggle against enemies with high saving throws for their chosen abilities.
• Damage Dice and Bonuses: The combination of damage dice (number and size) and additional flat damage determines the potential damage output. Weapons with larger dice or higher bonuses, especially those that synergize with character abilities (like a fighter’s Strength modifier), will yield higher average damage.
• Critical Hit Mechanics: Critical hits can drastically swing combat. A higher critical multiplier or abilities that grant critical hits on lower rolls significantly boost damage output over time. Understanding when and how often you crit is vital for assessing offensive power.
• Action Economy: Pathfinder 2e uses an action point system. While a calculator might show the damage per attack, it doesn’t inherently account for how many attacks you can make per turn. Abilities like Flurry of Blows (Monk) or Rapid Shot (Ranger) increase the number of attacks, thereby increasing total damage output per round, even if individual attack chances decrease. This is a critical aspect of optimizing your Pathfinder 2e character.
• Circumstance and Status Bonuses/Penalties: These temporary modifiers can significantly alter attack rolls and damage. Being inspired, using tactical positioning, or benefiting from helpful spells grants bonuses, while facing certain enemies or environmental hazards can impose penalties. These dynamic changes are what make combat exciting but are hard to predict perfectly in a static calculator.
• Debuffs and Buffs: Enemies might use abilities that lower your attack bonus or damage, while allies might cast spells or use feats that enhance them. These effects are crucial and can dramatically shift the probabilities calculated.
• Number of Enemies and Encounter Difficulty: The calculator typically focuses on a single attacker versus a single defender. In practice, facing multiple weaker enemies might require different tactics than facing one powerful boss, even if the raw damage numbers seem comparable. Effective Pathfinder 2e encounter building considers action economy and threat.

Frequently Asked Questions (FAQ)

What does a ‘natural roll’ mean in Pathfinder 2e?

A natural roll refers to the number that appears directly on the 20-sided die (d20) before any modifiers are applied. For example, rolling a 15 on the die is a natural 15. Natural 1s and 20s have special critical success and critical failure effects, respectively.

How does the calculator handle critical hits?

The calculator determines critical hits based on two conditions: rolling a natural 20, or rolling a natural die result that is 10 or more higher than the minimum roll needed to hit the target AC. The damage from a critical hit is calculated using the critical hit multiplier (usually x2) on the damage dice, plus any additional flat damage.

My character has multiple attacks. How does the calculator account for this?

If you input ‘Number of Attacks’ greater than 1, the calculator will provide the average damage per individual attack (factoring in misses, hits, and crits) and also an overall “Hit Chance” which represents the cumulative probability of at least one attack hitting. It does not typically account for the penalty to subsequent attacks in a multi-attack action unless specified by advanced options (which this basic calculator does not have).

What if the needed roll to hit is very low or very high?

Pathfinder 2e has specific rules for extreme rolls. A natural 1 always results in a critical failure, regardless of modifiers. A natural 20 always results in a critical success, provided it would have hit normally. If the ‘needed roll to hit’ is 21 or higher, you automatically miss unless you roll a natural 20. If the ‘needed roll to hit’ is 0 or lower, you automatically hit unless you roll a natural 1. The calculator is designed to interpret these rules to provide accurate hit and critical hit chances.

Can this calculator predict my exact damage in a specific combat?

No, this calculator provides average damage and probabilities. Actual combat results are subject to the randomness of dice rolls. The calculator is a tool for understanding statistical likelihoods and optimizing average performance, not for guaranteeing specific outcomes.

What is the difference between ‘Avg Damage Per Hit’ and ‘Avg Damage Per Attack’?

‘Avg Damage Per Hit’ tells you the average damage dealt *only when an attack successfully hits*. ‘Avg Damage Per Attack’ is a more comprehensive metric that factors in the probability of missing entirely, hitting normally, or critically hitting, providing a realistic average damage output across all attack attempts.

How should I use the results to make decisions?

Use the Hit Chance to gauge the reliability of your attacks. If it’s low against a tough enemy, consider using actions that boost your attack bonus or reduce the enemy’s AC. Use the Average Damage Per Attack to compare the effectiveness of different weapons or combat styles. If average damage is low, look for ways to increase your damage dice, add flat bonuses, or capitalize on critical hits.

Are there special rules for critical fails?

Yes, a critical failure typically means the effect fails in a spectacular way. For attacks, it might mean dropping your weapon, hitting an ally, or suffering a disadvantage. The calculator focuses on the attack roll’s success/fail state, but the GM determines the specific narrative consequences of a critical failure.

Damage vs. Hit Chance Analysis

This chart visualizes the trade-off between average damage per attack and the probability of hitting for different attack bonuses against a static AC. Notice how increasing attack bonus increases hit chance, but damage per hit remains constant unless the bonus itself affects damage.