Damage

Overview

In Factorio, entities have health, can die/be destroyed, and have resistances. Damage is defined as the concept of lowering an entity's health by using an attack, such as a gun firing at it, or a biter chewing on it. An entity's resistances will define exactly how much damage the entity will take off of an arbitrary attack.

The character's maximum health is 100 (without energy shields). Other entities' health values are listed in their individual entries.

Achievements

The concept of damage is directly connected to the following achievements:

Run Forrest, run Destroy 100 trees by impact.

Pyromaniac Destroy 10k trees with fire.

Steamrolled Destroy 10 spawners by impact.

Golem Survive a hit of 500 damage or more.

Watch your step Get killed by a moving locomotive.

Damage Types

Damage type	Used by
Physical	Bullets (regular/piercing/uranium), shotgun (regular/piercing), biters, axe (iron/steel), defender robots
Impact	Collision (of train/car)
Fire	Flamethrower
Acid	Worm Turrets, Spitters
Poison	Poison capsule
Explosion	Rockets, Explosive Rockets, Grenade, Cluster grenade
Laser	Laser turrets, distractor/destroyer robots, personal laser defense

Resistance

Resistance has two aspects:

• Percentile resistance

Percentile resistance reduces the damage by the specified percent. If the percentage is 100%, the entity is immune to the damage. As an example, an entity having 25% resistance to 100 bullet damage would take 75 damage instead.

• Decrease, or "flat" resistance

Decrease resistance decreases the damage by specified number as long as the result damage wouldn't be less than zero. If the result damage would be less than 0, the extra resistance is used as denominator in the fraction of damage that is going to be dealt.

Display of resistances

In Factorio, resistances are displayed as such:

Decrease resistance/Percent resistance

So, an entity displaying 10/20% resistance to fire means that that entity has 10 flat resistance and 20% percentile resistance to fire. So, if said entity were to take 30 fire damage, they would instead take 16 damage, after resistances were applied.

Formulas

Decrease < Damage

Result damage = (Damage - Decrease) * (1 - Percentage)

Decrease >= Damage

Result damage = 1 / (2 + Decrease - Damage) * (1 - Percentage)

An example table of different resistances and what the result damage would be:

Damage	Resistance	Result damage (0% damage loss)
5	0	5
5	1	4
5	2	3
5	3	2
5	4	1
5	5	1/2
5	6	1/3
5	7	1/4
5	8	1/5
...	...	...