FEH Damage Calculator

Your essential tool for theorycrafting in Fire Emblem Heroes. Predict combat outcomes, optimize builds, and secure victory with this powerful feh damage calculator.

What is the FEH Damage Calculator?

The feh damage calculator is a specialized tool designed for players of Fire Emblem Heroes to simulate and predict the outcome of a single combat exchange. Unlike a generic calculator, it incorporates the core mechanics of the game’s combat system, including Attack (Atk), Defense (Def), Resistance (Res), weapon triangle advantage (WTA), and weapon effectiveness. By inputting the stats of both an attacking and a defending unit, players can instantly see how much damage will be dealt.

This is invaluable for theorycrafting new hero builds, testing matchups in Aether Raids or Arena, and understanding precisely how different skills interact. Whether you’re a new player learning the ropes or a veteran planning for the next meta, a reliable feh damage calculator is one of the most important resources you can have. To better understand how skills change these numbers, see our guide to understanding FEH skills.

FEH Damage Formula and Explanation

The core damage calculation in Fire Emblem Heroes is a multi-step process. While many skills can add complexity, the basic formula is straightforward. Our feh damage calculator simplifies this into an easy-to-use interface.

The fundamental formula is:
Final Damage = ( ( floor(Atk * WTA) * Effectiveness ) - Defender's Stat ) * (1 - % Reduction) + Bonus Damage

This calculation happens in stages. First, the attacker’s Atk is modified by the weapon triangle, then that result is multiplied by effectiveness, and finally the defender’s stat is subtracted. Decimals are dropped at key steps.

Formula Variables

Variables used in the FEH damage calculation.

Variable	Meaning	Unit / Type	Typical Range
Atk	Attacker’s total in-combat Attack stat.	Points	40 – 100+
WTA	Weapon Triangle Advantage modifier.	Multiplier	0.8x, 1.0x, 1.2x
Effectiveness	“Effective against” weapon bonus.	Multiplier	1.0x or 1.5x
Defender’s Stat	Defender’s Def (vs. physical) or Res (vs. magical).	Points	20 – 80+
% Reduction	Percentage-based damage reduction skills.	Percentage	0% – 80%

Practical Examples

Example 1: Classic Weapon Triangle Advantage

Imagine a modern speedy sword unit attacking a green axe unit.

• Inputs:
  • Attacker’s Atk: 70
  • WTA: Advantage (+20%)
  • Effectiveness: No
  • Defender’s Def: 45
  • Damage Reduction: 0%
  • Bonus Damage: 0
• Calculation:
  1. Effective Atk = floor(70 * 1.2) = 84
  2. Base Damage = 84 – 45 = 39
  3. Final Damage = 39
• Result: The sword unit deals 39 damage. A solid one-hit KO on many axe units. The right matchup can make all the difference, a key part of our team building basics guide.

Example 2: Tanking with Damage Reduction

Now, consider a powerful bow unit attacking a modern infantry tank with damage reduction skills.

• Inputs:
  • Attacker’s Atk: 75
  • WTA: Neutral
  • Effectiveness: Yes (Bow vs. Flier, but let’s assume target is infantry)
  • Defender’s Def: 40
  • Damage Reduction: 40%
  • Bonus Damage: 10 (from a skill like Deadeye)
• Calculation:
  1. Effective Atk = floor(75 * 1.0) = 75
  2. Base Damage = 75 – 40 = 35
  3. Damage Mitigated = floor(35 * 0.40) = 14
  4. Final Damage = (35 – 14) + 10 = 31
• Result: The defender takes 31 damage. Without damage reduction, they would have taken 45 damage (35 base + 10 bonus), showing how crucial these skills are in the modern meta. For units that excel at this, check our list of the best nuke units in FEH.

How to Use This FEH Damage Calculator

Using this calculator is a simple, step-by-step process:

1. Enter Attacker Stats: Input the attacker’s total in-combat Atk stat. This should include all buffs from skills like Atk/Spd Catch, Blade Session, etc.
2. Set Combat Modifiers: Use the dropdown to select the weapon triangle situation (Advantage, Disadvantage, or Neutral). Check the box if the attacker’s weapon is “effective against” the defender’s movement or weapon type.
3. Enter Defender Stats: Input the defender’s relevant defensive stat (Def for swords, lances, axes, bows, daggers; Res for tomes, staves, dragons). Also, input their total percentage-based damage reduction.
4. Add Bonus Damage: If any skills or specials (like Glimmer, Bonfire, or true damage effects) will activate, add that flat damage here.
5. Review Results: The calculator will instantly update the “Final Damage” and the intermediate values, giving you a complete picture of the combat. You can even see how the numbers compare in the dynamic chart and table.

Interpreting the results is key. A high damage number might confirm a build’s effectiveness, while a low number might suggest you need a different approach or support. This kind of analysis is central to our latest FEH meta report.

Key Factors That Affect FEH Damage

Many factors beyond the basic stats influence the final damage number. Here are six of the most important:

• In-Combat Stat Swings: Skills like Ideals, Catches, and Solos can dramatically change stats during combat, far beyond visible buffs.
• Weapon Triangle Manipulation: Skills like Triangle Adept or the Cancel Affinity effect can alter the standard +/- 20% WTA modifier to +/- 40% or negate it entirely, completely changing a matchup.
• Specials: Offensive specials can add flat damage (Glimmer, Moonbow), scale off stats (Bonfire, Iceberg), or even ignore a percentage of the foe’s defenses (Luna), making them a massive source of damage.
• Damage Reduction: The single most important defensive mechanic. Skills that grant “damage reduction by X%” can allow units to survive otherwise lethal hits. It’s a cornerstone of modern tanking.
• True Damage: This is flat, bonus damage (often from skills like Wrath or special effects) that is added *after* all other calculations and is not reduced by Def/Res or most damage reduction skills.
• Support: Don’t forget support units! Allies can provide extra stats, special charge, or unique effects like nullifying enemy skills, all of which indirectly but significantly impact the damage of your main unit. A good starting point is our FEH beginner’s guide which covers team synergy.

Frequently Asked Questions (FAQ)

1. What is WTA in the feh damage calculator?

WTA stands for Weapon Triangle Advantage. In FEH, Red has an advantage over Green, Green over Blue, and Blue over Red. This gives a +/- 20% modifier to the Atk stat during damage calculation.

2. How does “effective against” damage work?

If a weapon is “effective against” a certain type (e.g., a bow against a flier), it multiplies the user’s Atk by 1.5 during that combat, before the defender’s stats are subtracted.

3. Does this calculator account for all skills like Null Follow-Up or Guard?

No. This is a damage calculator, not a full combat simulator. It calculates the damage of a single hit. It does not account for skills that affect the number of hits (Brave, Null Follow-Up) or special charge (Guard, Breath skills). You can, however, simulate some skill effects by manually adjusting the input values.

4. What’s the difference between Def and Res?

Defense (Def) reduces damage from physical weapons (swords, lances, axes, bows, daggers, beasts). Resistance (Res) reduces damage from magical weapons (tomes, staves, dragons).

5. How do I calculate my unit’s total in-combat Atk?

Start with the unit’s visible Atk stat. Add any visible buffs (from Rally skills, for example). Then, add any in-combat buffs from their own skills (like Atk/Spd Catch) and support allies (like Drive Atk).

6. Why is the calculated damage result 0?

If the defender’s Def/Res is higher than the attacker’s final Atk after all multipliers, the base damage will be less than zero. In FEH, an attack can never do less than 0 damage, so the result is floored at 0.

7. How does damage reduction stacking work?

Multiple sources of damage reduction stack multiplicatively, not additively. For example, two sources of 40% reduction result in 64% total reduction (1 – (1 – 0.4) * (1 – 0.4)), not 80%. This calculator requires you to enter the final, combined percentage.

8. What is “True Damage” and how do I input it?

True Damage is a term for bonus damage that isn’t reduced by defenses. This includes effects like Wo Dao’s +10 on special trigger or Wrath’s bonus. You should add all sources of true damage into the “Bonus Damage” field of the feh damage calculator.