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+

Units in red are Brood War units.

* Weapon does splash damage to all units
+ Weapon does friendly splash damage (meaning it will hit allies and enemy units but not your own)