# What do carapace upgrades do for damage in Starcraft 2

How does a zerg carapace upgrade change inflicted damage on a unit? Is it worth purchasing?

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The equation is very simple for armor (much simpler than Warcraft 3 for example).

Each unit has a number of attacks. Zealots for example hits 2 times for 8 damage each shot

Each unit has a number of armor points. Each armor point reduces damange by 1 by attack

Each race can upgrade armor (protoss shield works the same way). Each armor upgrade gives +1 armor.

So if a zealot would hit a zergling with carapace upgrade 1 (Total armor = 1) the calculation is as follow

(8 - 1) x 2 = 14 total damage


Now Starcraft 2 units gets bonuses versus particular types of units

Suppose that a Viking (2x6 +8 vs armored) would try to shoot down a battlecruiser (3 armor). The calculation goes like this

(6 + 8 - 3) x 2 = 22 damage


So you can say that multiple hits is a weakness, since the armor gets deduced multiple times.

Now for the second part of your question, is carapace upgrade worth it? I'd say yes, but the real answer is "it depends on when to get it". Starcraft is a game of tradeoffs, so getting upgrades is good, but losing because your enemy has more units/firepower than you is bad.

The question becomes "when is it safe to upgrade?". As a rule of thumb, I'd say that whenever the game gets lengthy, that you can secure an expansion for the extra gas this cost, do it.

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(6 + 8 - 3) x 2 = 22 damage for clarification, Are you sure the damage bonus vs massive isn't added after the calculation for damage of the two attacks? such as (6 - 3 ) x 2 + 8 = 14. the way you describe it means you're putting a +8 on every attack made, when it does two attacks per cycle. I could see this as making viking a huge anti-cap ship weapon with relative ease. 10 vikings = dead BC ball or dead carrier ball. OTOH, Zerg has no such weapon, and must rely on cooldown based castable and mass corruptor, which I've personally found isn't very effective. –  user8782 Apr 18 '11 at 23:36

Zerg carapace functions the same as other races' armor upgrades, it reduces the damage taken from each incoming shot by 1 per level of carapace. Because of this it is most effective against things that do their damage in lots of smaller shots (such as marines and battlecruisers) rather than heavy-hitting units like siege tanks and ultralisks. That being said, it is usually worthwhile to upgrade your units (at least the type you plan to rely on the most) provided the game makes it to midgame or later.

Worth special mention: Zealots will kill a zergling in two hits instead of three as long as their attack upgrade is at least 1 higher than the zergling's carapace upgrade.

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I personally will almost always do level 1 carapace on any of my units. You really never know when the tech switch will hit and you need to flip from ground to air or vice versa. –  Robb Aug 26 '10 at 5:34
@Robb If the game goes late enough then yes, I will usually end up with 2/2 or better on both ground and air units. However, in almost all cases I get attack upgrades before armor and the gas required to get armor and attack for all your units is a bit much in the early to mid game. Also, against builds like terran mech ground armor tends to seem a bit silly to get before ultras...I don't care whether my zergling is over-killed by 15 damage or by 14 :-P –  en1gmatic325 Aug 26 '10 at 5:58