Units in StarCraft are one of three different sizes: small, medium and large. The size of a unit is taken into account when calculating the effects of different classes of damage. This is why, for example, a Firebat is very effective against Marines, but has a minimal effect on Siege Tanks. The damage classes and their effectiveness in relation to the three unit sizes are as follows:
* Normal weapons are equally effective against all types of units.
* Concussion/Plasma weapons do 50% damage against Medium units and 25% against Large units.
* Explosive weapons do 50% damage against Small units and 75% against Medium units.
Protoss shields always take full damage from all attacks. Buildings are considered "Large" units.
Some attacks, such as the Scarab explosion, also do "splash damage", which means that any units or buildings within a short radius of the attack point will take a peripheral amount of damage.
The following table lists each unit's size and damage type:
Terran Units
Unit Size Ground Attack Air Attack
SCV Small Normal -
Marine Small Normal Normal
Firebat Small Concussive+ -
Ghost Small Concussive Concussive
Vulture Medium Concussive -
Siege Tank – Tank Large Explosive -
Siege Tank – Siege Large Explosive* -
Goliath Large Normal Explosive
Wraith Large Normal Explosive
Dropship Large - -
Science Vessel Large - -
Battlecruiser Large Normal Normal
Medic Small - -
Valkyrie Large - Explosive+
Zerg Units
Unit Size Ground Attack Air Attack
Larva Small - -
Drone Small Normal -
Zergling Small Normal -
Hydralisk Medium Explosive Explosive
Ultralisk Large Normal -
Infested Terran Small Normal* -
Broodling Small Normal -
Defiler Medium - -
Queen Medium - -
Overlord Large - -
Scourge Small - Normal
Mutalisk Small Normal Normal
Guardian Large Normal -
Lurker Medium Normal+ -
Devourer Large - Explosive
Protoss Units
Unit Size Ground Attack Air Attack
Probe Small Normal -
Zealot Small Normal -
Dragoon Large Explosive Explosive
High Templar Small - -
Archon Large Normal+ Normal+
Reaver Large Normal+ -
Shuttle Large - -
Observer Small - -
Scout Large Normal Explosive
Carrier Large - -
Interceptor Small Normal Normal
Arbiter Large Explosive Explosive
Dark Archon Large - -
Dark Templar Small Normal -
Corsair Medium - Explosive+
* Weapon does splash damage to all units
+ Weapon does friendly splash damage (meaning it will hit allies and enemy units but not your own)