Every hit in NS2 goes through the same short formula. Once you know it, hits-to-kill numbers, combos and upgrade choices all make sense. How armor soaks what is left is on Armor.
How one hit is calculated#
How a hit splits, by damage type#
The same 100 damage, against a marine and an exosuit with plenty of armor left:
| Damage type | vs Marine (100 damage) | vs Exosuit (100 damage) |
|---|---|---|
| Normal Rifle, bite, spit, mines | 7030100 dmg · costs 35 armor | 100100 dmg · costs 50 armor |
| Light (unused by player weapons) | 7030100 dmg · costs 17.5 armor | 100100 dmg · costs 25 armor |
| Heavy Minigun, Stomp | 7030100 dmg · costs 70 armor | 100100 dmg · costs 100 armor |
| Puncture Swipe, spikes | 14060200 dmg · costs 70 armor | 200200 dmg · costs 100 armor |
| MachineGun Heavy Machine Gun | 10545150 dmg · costs 52.5 armor | 150150 dmg · costs 75 armor |
| Structural Axe, stab, gore, railgun | 7030100 dmg · costs 35 armor | 100100 dmg · costs 50 armor |
| Gas Spores | 100100 dmg · costs 0 armor | no damage |
| Corrode Bile Bomb | 1212 dmg · costs 6 armor | 4040 dmg · costs 20 armor |
absorbed by armor · taken by health. Assumes the target still has plenty of armor; once armor runs out everything goes to health.
All damage types#
| Type | Effect | Used by |
|---|---|---|
| Normal | No modifiers |  Rifle,  pistol,  bite,  spit,  mines, sentries, hydras,  ARC shells |
| Light | Armor absorbs double (4 per point) | – |
| Heavy | Armor absorbs half (1 per point) |  Minigun,  Stomp |
| Puncture | ×2 against players and exos |  Swipe,  spikes |
| Structural | ×2 against structures |  Axe,  Railgun,  Stab,  Gore |
| Machine gun | ×1.5 against players |  Heavy Machine Gun |
| Grenade launcher | ×4 against structures |  Grenade Launcher |
| Flame | ×2 against structures, a further ×2.5 against flammable ones; sets targets on fire |  Flamethrower,  Welder |
| Cluster flame | ×2.5 against structures (plus fire), ×0.2 against players |  Cluster grenade |
| Gas | Ignores armor; only hurts breathing targets (marines) |  Spores |
| Nerve gas | Aliens only, armor only |  Nerve gas |
| Corrode | Full damage to structures; ×0.4 to exos; ×0.12 to marines and armor only |  Bile Bomb, Bombard, Contamination |
| Biological | Only hurts living targets | Heal spray |
| Splash | Structures only (including your own ARCs) | ARC |
| Falling | Ignores armor | Fall damage |
Flammable targets are cysts, eggs, hydras, clogs, webs, babblers, bone walls and contamination.
Damage upgrades#
Marine weapon upgrades#
| Level | Most weapons | Shotgun | Grenade Launcher, Flamethrower |
|---|---|---|---|
 W1 | ×1.1 | ×1.078 | ×1.07 |
 W2 | ×1.2 | ×1.157 | ×1.14 |
 W3 | ×1.3 | ×1.235 | ×1.21 |
Weapon upgrades only matter when they cross a breakpoint: W1 takes a rifle from 10 to 9 bullets on a fresh skulk. The Hits to kill calculator shows every breakpoint by biomass.
Alien damage upgrades#
Focus: main attack +11% damage per Veil (up to +33%), attacking slower. One Veil already gives the 2-bite skulk on an A0 marine.
Crush: 7% per Spur. Against exos and structures it is plain extra damage (+21% at 3 Spurs). Against marines it does something else: armor absorbs a bigger share of each hit (91% instead of 70% at 3 Spurs), so armor is stripped faster but the hits to kill don't change; see Crush against marines.- Melee alien attacks never get weapon upgrades.
Friendly fire#
Friendly fire is on: your own grenades, flames and bile hurt teammates for 33% of normal damage (and yourself).
Other modifiers#
Nano Shield multiplies damage taken by 68%.
Umbra multiplies bullet and grenade damage by 80%.
Mucous Membrane and 
babblers add shields that soak damage first.
Bone Shield absorbs frontal hits into its own hit points.