Upgrades include anything that improves the functionality of your units. There are numerical upgrades and qualitative upgrades. For a strategical look on Upgrades, consult The Importance of Upgrades. While building, upgrades can be cancelled for a full refund. If the building upgrading dies during the upgrade, only 75% of the cost is refunded.
Numerical Upgrades have three tiers with equal effects but increasing cost. They affect a class of units, increasing their damage or survivability. For all races, air and ground units are treated seperately. For Terran, ground units are split into mechanic and bionic. For Zerg, ground attack upgrades are split into melee and ranged.
Numerical Upgrades are performed in a single generalized building. Qualitative Upgrades are most frequently available at the building that enables the construction of the unit. (e.g. Observer Upgrades at Observatory, Ultralisk Upgrades at Ultralisk Cavern).
There are two kinds of Numerical Upgrades, attack and armor. Armor Upgrades are more expensive than Attack Upgrades of the same tier.
These increase the damage dealt by all units of the class by [number of upgrades] * x, where x is some attack modification specific to each unit. The magnitude of x is roughly determined by the unit's base damage, divided by 10. E.g. Archons gain +3 Damage, since their basic damage is 30, while Marines gain +1, since their basic damage is 6. Some units upgrade better than others. For example, the Goliath's anti-air base damage is 20 with +4 per upgrade, while a Dragoon's base damage is also 20 with only +2 per upgrade.
Each Armor Upgrade increases the armor of a class of units by +1. Most unit classes have a singular attack upgrade and a singular defense upgrade, except for the Protoss: Here, ground units and air units have seperate defensive upgrades, but a shared shield upgrade, which is even more expensive than the armor upgrade.
- Terran Infantry: Engineering Bay; Terran Mech and Air: Armory.
- Protoss Ground Units and Shields for all units and buildings: Forge; Protoss Air Units: Cybernetics Core.
- Zerg Ground Units: Evolution Chamber; Zerg Air Units: Spire / Greater Spire.
- Qualitative Upgrades, in most cases, affect how units function apart from their numerical combat effectiveness.
- Metabolic Boost: Zergling +50% 100 100 100
- Muscular Augments: Hydralisk +50% 150 150 100
- Pneumatized Carapace: Overlord +400% 150 150 133
- Anabolic Synthesis: Ultralisk +50% 200 200 133
- Gravitic Drive: Shuttle +50% 200 200 166
- Gravitic Thrusters: Scout +33% 200 200 166
- Gravitic Boosters: Observer +50% 150 150 133
- Leg Enhancements: Zealot +50% 150 150 133
- Ion Thrusters: Vulture +50% 100 100 100
- Grooved Spines: Hydralisk +1 to 5 150 150 100
- Singularity Charge: Dragoon +2 to 6 150 150 166
- U-238 Shells: Marine +1 to 5 150 150 100
- Charon Boosters: Goliath +3 air weapons to 8 100 100 133
- Siege Tech: Gives the Siege Tank Siege Mode, which boosts range +5 to 12. (Also classified as an Other Upgrade) 150 150 80
- Spell Upgrades: Make a specific spell available to the caster.
- High Templar
- Dark Archon
- Develop Disruption Web
- Research Cloaking Field
- Research Yamato Cannon
- Energy Upgrades: Increase the maximum energy for the caster from 200 to 250. Also increases the Energy when spawning from 50 to 62.5 (except for Dark Archons, as they technically don't spawn), but only if the upgrade was finished before unit making was begun.
- Gamete Meiosis (Queen) 150 150 166
- Metasynaptic Node (Defiler) 150 150 166
- Khaydarin Amulet (High Templar) 150 150 166
- Argus Talisman (Dark Archon) 150 150 166
- Khaydarin Core (Arbiter) 150 150 166
- Argus Jewel (Corsair) 100 100 166
- Apollo Reactor (Wraith) 200 200 166
- Moebius Reactor (Ghost) 150 150 166
- Colossus Reactor (Battlecruiser) 150 150 166
- Titan Reactor (Science Vessel) 150 150 166
- Caduceus Reactor (Medic) 150 150 166
- Increases the sight and detection range of a specific unit by 2 (from 9 to 11 except the Scout which is 8 to 10):
- Antennae (Overlord) 150 150 133
- Sensor Array (Observer) 150 150 133
- Apial Sensors (Scout) 100 100 166
- Ocular Implants (Ghost) 100 100 166
- Reaver Scarabs: 5 --> 10 200 200 166
- Carrier Interceptors: 4 --> 8 100 100 100
- Evolve Lurker Aspect: Hydralisks gain the ability to morph into Lurkers. 200 200 120
- Chitinous Plating: Ultralisk armor is increased by +2 in addition to the regular armor upgrades. 150 150 133
- Ventral Sacs: Overlords gain the ability to carry and drop ground units. Like all drop units this has 8 slots. 200 200 160
- Adrenal Glands: Zerglings get an upgrade to increase their rate of attack. 200 200 100
- Scarab Damage: The Reaver increases its Scarab damage by 25, to 125. 200 200 166
- Siege Tech: Siege Tanks gain the abilitiy to change to Siege Mode, increasing their range and damage while remaining stationary. 150 150 80
- Spider Mines: Vultures gain 3 Spider Mines that can be set in the ground. 100 100 80
- Stim Pack Tech: Marines and Firebats get increased movement speed and rate of attack for a limited amount of time at the cost of 10 health. 100 100 80