PF2e Combat Calculator

Accurately predict your Pathfinder 2nd Edition combat outcomes.

PF2e Combat Calculator

Enter your character’s attack details and the target’s defenses to calculate average damage and hit probabilities for your Pathfinder 2nd Edition strikes.

What is a PF2e Combat Calculator?

A PF2e Combat Calculator is an invaluable digital tool designed for players and Game Masters (GMs) of Pathfinder 2nd Edition. It helps to predict the statistical outcomes of combat encounters by calculating the probabilities of hitting, critically hitting, missing, or critically failing an attack, as well as the average damage dealt per strike. This goes beyond simply rolling dice; it provides a deeper understanding of the underlying math that governs combat in PF2e.

Who should use a PF2e Combat Calculator?

• Players: To optimize character builds, choose feats, weapons, and spells that maximize their combat effectiveness, and understand the impact of various buffs and debuffs.
• Game Masters: To design balanced encounters, assess the threat level of monsters, and quickly determine the average damage output of NPCs.
• Character Builders: For theorycrafting and comparing different build paths, ensuring their character performs as expected in combat.
• New Players: To demystify the combat rules and gain a clearer picture of how their choices affect their chances of success.

Common Misconceptions about a PF2e Combat Calculator:

• It replaces dice rolls: Absolutely not! The calculator provides averages and probabilities, but the actual outcome of any given attack still depends on the luck of the dice. It’s a predictive tool, not a substitute for gameplay.
• It accounts for every rule: While comprehensive, a general PF2e Combat Calculator typically focuses on core attack and damage mechanics. Specific feats, reactions, or unique monster abilities might not be directly factored in unless explicitly added as inputs.
• It guarantees success: Understanding probabilities increases your chances, but it doesn’t eliminate randomness. A low-probability critical hit can still happen, and a high-probability hit can still miss.

PF2e Combat Calculator Formula and Mathematical Explanation

The core of any PF2e Combat Calculator lies in its ability to accurately model the d20 roll system and damage calculations. Here’s a step-by-step breakdown of the formulas used:

Step-by-Step Derivation:

1. Determine Effective Attack Modifier and Target AC:
   • Effective Attack Modifier = Base Attack Modifier + Circumstance Bonuses (e.g., Flanking) + Status Bonuses - Penalties (e.g., MAP)
   • Effective Target AC = Base Target AC - Circumstance Penalties (e.g., Flat-Footed) - Status Penalties (e.g., Frightened)
2. Calculate Required d20 Rolls:
   • Roll Needed for Normal Hit = Effective Target AC - Effective Attack Modifier
   • Roll Needed for Critical Success = Roll Needed for Normal Hit - 10
   • Roll Needed for Critical Failure = Roll Needed for Normal Hit + 10
3. Calculate Probabilities for Each Outcome (d20 roll from 1 to 20):
   • Critical Success (P_CritSuccess): Occurs on a natural 20, OR if the d20 roll is 10 or more greater than the Roll Needed for Normal Hit (i.e., roll >= Roll Needed for Critical Success).
   • Normal Hit (P_NormalHit): Occurs if the d20 roll is greater than or equal to the Roll Needed for Normal Hit, but not a Critical Success, AND not a natural 1.
   • Critical Failure (P_CritFailure): Occurs on a natural 1, OR if the d20 roll is 10 or more less than the Roll Needed for Normal Hit (i.e., roll < Roll Needed for Critical Failure).
   • Normal Miss (P_NormalMiss): Occurs if the d20 roll is less than the Roll Needed for Normal Hit, but not a Critical Failure, AND not a natural 20.
   • The sum of these probabilities must equal 1 (or 100%). Each outcome's probability is its count of successful rolls divided by 20.
4. Calculate Average Damage for Normal Hit:
   • Average Dice Roll = (Dice Type / 2) + 0.5 (e.g., d6 = 3.5)
   • Base Damage = (Damage Dice Count * Average Dice Roll) + Flat Damage Bonus
   • Damage on Normal Hit = MAX(0, Base Damage + Weakness Value - Resistance Value)
5. Calculate Average Damage for Critical Hit:
   • Critical Hit Damage = (Base Damage * 2) + (Crit Spec Dice Count * Average Crit Spec Dice Roll)
   • Damage on Critical Hit = MAX(0, (Base Damage * 2) + (Crit Spec Dice Count * Average Crit Spec Dice Roll) + Weakness Value - Resistance Value)
   • Note: Weakness/Resistance applies once per damage instance. For a critical hit, the base damage is doubled, then weakness/resistance is applied, then critical specialization damage is added.
6. Calculate Overall Average Damage per Strike:
   • Overall Avg Damage = (P_CritSuccess * Damage on Critical Hit) + (P_NormalHit * Damage on Normal Hit)

Variable Explanations and Table:

Understanding the variables is crucial for using any PF2e Combat Calculator effectively.

Key Variables for PF2e Combat Calculations

Variable	Meaning	Unit	Typical Range
Attack Modifier	Your total bonus to attack rolls.	+X	+5 to +30
Target AC	The Armor Class of the creature you are attacking.	AC	15 to 45
Damage Dice Count	Number of dice rolled for weapon damage.	Dice	1 to 4+
Damage Dice Type	Type of dice rolled for weapon damage (e.g., d6, d8).	Dice Type	d4, d6, d8, d10, d12
Flat Damage Bonus	Any static bonus added to damage (e.g., Strength modifier, weapon runes).	+X	+0 to +15
Crit Spec Damage	Additional damage dice from critical specialization effects (e.g., Deadly, Fatal).	Dice	0 to 3+
Multiple Attack Penalty (MAP)	Penalty applied to subsequent attacks in a turn.	-X	-5, -10
Flanking	A circumstance bonus to attack rolls when flanking an enemy.	+2	0 or +2
Frightened Value	A status penalty to target AC from the Frightened condition.	-X	-1 to -4
Weakness Value	Additional damage dealt to a target with a specific weakness.	+X	+0 to +50
Resistance Value	Damage reduction against a specific type of damage.	-X	-0 to -50

Practical Examples (Real-World Use Cases)

Let's look at how a PF2e Combat Calculator can be used in practice.

Example 1: Basic Fighter Strike

Consider a 5th-level Fighter with a +13 Attack Modifier, wielding a greatsword (2d12 damage) with a +6 flat damage bonus. They are attacking a standard Ogre with an AC of 20. The Ogre has no special conditions.

• Inputs:
  • Attack Modifier: 13
  • Target AC: 20
  • Damage Dice Count: 2
  • Damage Dice Type: d12
  • Flat Damage Bonus: 6
  • Crit Spec Damage Dice Count: 0
  • Crit Spec Damage Dice Type: d6 (irrelevant if count is 0)
  • MAP: No
  • Flanking: No
  • Frightened: No
  • Weakness: No
  • Resistance: No
• Outputs (from PF2e Combat Calculator):
  • Chance of Critical Success: 25.00% (Roll 7 or higher for crit, or natural 20)
  • Chance of Normal Hit: 45.00% (Roll 17 or higher for hit, but not crit, or natural 19)
  • Chance of Miss/Critical Failure: 30.00%
  • Average Damage on Normal Hit: 19.00 (2d12 avg 13 + 6)
  • Average Damage on Critical Hit: 38.00 (19 * 2)
  • Overall Average Damage (1st Strike): 14.25
• Interpretation: This fighter has a good chance to hit and crit, dealing significant average damage. This helps a player understand their character's baseline effectiveness.

Example 2: Flanked, Frightened, and MAP-affected Strike

Now, let's take the same Fighter, but they are making their second attack against the Ogre. The Ogre is Flanked and Frightened 2. The Fighter's MAP is -5 for the second attack.

• Inputs:
  • Attack Modifier: 13 (base)
  • Target AC: 20 (base)
  • Damage Dice Count: 2
  • Damage Dice Type: d12
  • Flat Damage Bonus: 6
  • Crit Spec Damage Dice Count: 0
  • Crit Spec Damage Dice Type: d6
  • MAP: Yes (2nd attack, -5 penalty)
  • Flanking: Yes (+2 bonus)
  • Frightened: Yes (Value 2)
  • Weakness: No
  • Resistance: No
• Calculations:
  • Effective Attack Modifier for 2nd Strike: 13 (base) - 5 (MAP) + 2 (Flanking) = 10
  • Effective Target AC: 20 (base) - 2 (Frightened) = 18
• Outputs (from PF2e Combat Calculator for 2nd Strike):
  • Chance of Critical Success: 15.00%
  • Chance of Normal Hit: 45.00%
  • Chance of Miss/Critical Failure: 40.00%
  • Average Damage on Normal Hit: 19.00
  • Average Damage on Critical Hit: 38.00
  • Overall Average Damage (2nd Strike): 10.45
• Interpretation: Even with MAP, the combined effects of Flanking and Frightened significantly improve the Fighter's chances and average damage compared to a raw second attack. This demonstrates the power of teamwork and conditions in PF2e. The PF2e Combat Calculator helps quantify these tactical advantages.

How to Use This PF2e Combat Calculator

Using this PF2e Combat Calculator is straightforward, designed to give you quick and accurate insights into your combat effectiveness.

1. Input Your Attack Details:
   • Your Attack Modifier: Enter your total attack bonus, including proficiency, ability modifier, item bonuses, and any permanent status/circumstance bonuses.
   • Target's Armor Class (AC): Input the AC of the creature you are attacking.
   • Damage Dice Count & Type: Specify how many dice you roll for damage (e.g., 2) and what type (e.g., d6).
   • Flat Damage Bonus: Add any static bonuses to your damage roll (e.g., Strength modifier, weapon specialization, striking runes).
   • Critical Specialization Damage: If your weapon has a critical specialization effect (like Deadly or Fatal), enter the additional dice count and type.
2. Apply Conditions and Penalties:
   • Multiple Attack Penalty (MAP): Check the box if you want to see the impact of subsequent attacks. You can customize the -5 and -10 penalties if your character has abilities that modify them.
   • Target is Flanked?: Check this if the target is flanked, granting you a +2 circumstance bonus to your attack.
   • Target is Frightened?: Check this if the target is Frightened, and enter the Frightened value (e.g., 1, 2, or 3) which applies as a penalty to their AC.
   • Target has Weakness/Resistance?: Check these boxes and enter the respective values if the target has a weakness or resistance to your damage type.
3. Read the Results:
   • Overall Average Damage: This is the primary highlighted result, showing the expected damage per strike, factoring in all probabilities and damage types.
   • Intermediate Values: You'll see the precise percentage chance for a Critical Success, Normal Hit, and Miss/Critical Failure. Also, the average damage for a Normal Hit and a Critical Hit are displayed.
   • Detailed Strike Breakdown Table: If MAP is enabled, this table will show the probabilities and average damage for your 1st, 2nd, and 3rd attacks, allowing you to compare the diminishing returns.
   • Probability Distribution Chart: The bar chart visually represents the chances of each outcome, making it easy to grasp your attack's reliability.
4. Decision-Making Guidance:

   Use the results from the PF2e Combat Calculator to:

   • Evaluate if a specific attack is worth making (e.g., is a third attack with high MAP still effective?).
   • Compare different weapon choices or feat selections.
   • Understand the impact of applying conditions like Frightened or Flanked.
   • Help GMs gauge the difficulty of encounters and the effectiveness of their monsters.

Key Factors That Affect PF2e Combat Results

The outcome of combat in Pathfinder 2nd Edition is influenced by a multitude of factors. A good PF2e Combat Calculator helps you understand the weight of each.

1. Attack Modifier: This is arguably the most critical factor. A higher attack modifier directly increases your chances of hitting and critically hitting. It's built from your proficiency, ability score, item bonuses, and temporary status/circumstance bonuses. Investing in ways to boost this (e.g., weapon runes, skill training, buffs) is paramount.
2. Target AC: The enemy's Armor Class is the direct opposition to your attack modifier. Lowering an enemy's AC (e.g., via conditions like Flat-Footed or Frightened) is often as effective as raising your own attack modifier.
3. Damage Dice & Bonus: While hitting is important, dealing damage is the goal. The number and type of damage dice (e.g., 2d6 vs. 1d12) and any flat damage bonuses (e.g., from Strength, Striking runes, property runes) significantly impact your average damage output.
4. Critical Specialization Damage: Pathfinder 2e's critical hit system is powerful. Weapons with traits like Deadly or Fatal, or those that grant critical specialization effects, add substantial extra damage on a critical hit, making them highly desirable for damage-focused builds.
5. Multiple Attack Penalty (MAP): This is a core mechanic of PF2e combat. Subsequent attacks in a turn incur a significant penalty (typically -5 for the second attack, -10 for the third). Understanding MAP is crucial for deciding whether to make multiple attacks or use actions for other purposes (e.g., moving, feinting, casting a spell). The PF2e Combat Calculator clearly shows this drop-off.
6. Weakness & Resistance: These target-specific traits can dramatically alter damage. Weakness adds damage, while resistance reduces it. Exploiting weaknesses or bypassing resistances is a key tactical consideration. Remember, they apply once per instance of damage.
7. Conditions: Various conditions can significantly impact combat. Frightened reduces AC, Flat-Footed makes a target easier to hit, Stunned can prevent actions. Applying and exploiting conditions is a cornerstone of effective PF2e combat.
8. Teamwork and Positioning: Actions like Flanking (granting a +2 circumstance bonus to attack) or Aid (granting a bonus to an ally's roll) are powerful examples of how coordinated efforts can swing combat in your favor.

Frequently Asked Questions (FAQ)

Q: Does this PF2e Combat Calculator account for every feat and ability?

A: This calculator focuses on core attack and damage mechanics. While it includes common modifiers like Flanking, Frightened, and MAP, specific feats, reactions, or unique monster abilities that alter attack rolls or damage in complex ways might not be directly integrated. Always consult your GM for specific rule interpretations.

Q: How does the Multiple Attack Penalty (MAP) work in PF2e?

A: In Pathfinder 2nd Edition, after your first Strike or attack action in a turn, subsequent attacks incur a penalty. Typically, your second attack has a -5 penalty, and your third attack has a -10 penalty. Some weapons (like Agile weapons) reduce this penalty (e.g., -4/-8). This PF2e Combat Calculator allows you to factor in these penalties to see their impact.

Q: Can I use this calculator for spell attacks or ranged attacks?

A: Yes, if the spell or ranged attack requires an attack roll (e.g., a Ray of Frost spell attack roll, or a bow attack). Simply input your spell attack modifier or ranged attack modifier into the "Your Attack Modifier" field, and the relevant damage dice/bonus.

Q: How does Weakness and Resistance apply to damage?

A: Weakness and Resistance apply once per instance of damage. For example, if you deal 10 fire damage to a creature with Weakness 5 to fire, you deal 15 damage. If you critically hit for 20 fire damage, you deal 25 damage (20 + 5). Similarly, Resistance reduces damage once per instance. This PF2e Combat Calculator applies these values correctly.

Q: What's the difference between a status bonus and a circumstance bonus?

A: In PF2e, you can only benefit from the highest status bonus and highest circumstance bonus to a given statistic at any one time. They stack with each other, but not with themselves. For example, Flanking provides a circumstance bonus, while a Heroism spell provides a status bonus. Both can apply simultaneously.

Q: Is a natural 20 always a critical success in PF2e?

A: Yes, a natural 20 on the d20 roll for an attack is always a critical success, regardless of the target's AC or your attack modifier. Conversely, a natural 1 is always a critical failure.

Q: How accurate is this PF2e Combat Calculator?

A: This calculator uses the established mathematical rules of Pathfinder 2nd Edition to determine probabilities and average damage. As long as your inputs accurately reflect the in-game situation, the results are mathematically sound and highly accurate for predicting statistical outcomes.

Q: Can this calculator help me decide if a third attack is worth it?

A: Absolutely! By enabling the MAP option, the PF2e Combat Calculator will show you the significantly reduced hit chance and average damage for your second and third attacks. This allows you to make informed tactical decisions about whether to continue attacking or use your remaining actions for something else, like moving, guarding, or setting up an ally.

Related Tools and Internal Resources

Enhance your Pathfinder 2nd Edition experience with these other helpful tools and guides:

• PF2e Character Builder: Design and optimize your characters with ease.
• PF2e Spell Slot Tracker: Keep track of your spellcasting resources during adventures.
• PF2e Encounter Builder: Create balanced and challenging encounters for your party.
• PF2e Leveling Guide: Plan your character's progression from level 1 to 20.
• PF2e Condition Reference: Quickly look up the effects of various conditions in combat.
• PF2e Monster Stats: Access a database of monster statistics for GMs.