SCV repairing speed

1. How quickly do SCVs repair buildings/units?
2. How many SCVs are required to repair a supply depot/bunker/barracks being attacked by 2 zealots, by 4 stalkers, 1-2 void rays, 6 marines?

Any other valuable information about repairing is welcome.

Solution 1:

Actually, I believe repair time varies per unit. In general it is proportional to unit/building build time, but in some cases it is reported to vary.

The SCV wiki entry says that repair time is the same as build time; however, in some forum posts (post 1, post 2) people have said that the rate varies, and is defined in the SC2 editor.

The numbers given seem to say that a range of 5-20 DPS can be healed by 1 SCV, depending on the unit/building. However, some of those numbers are from last year, so they may have changed in recent patches.

Once you have the repair rate for the structure in question, you can refer to a unit DPS chart to calculate how many SCV's are needed to repair incoming damage.

Also, you didn't ask, but the cost of SCV repairs is 25% of original cost. That is, to fully repair a unit/structure will cost 25% of its original cost.

Solution 2:

Repair time is the same as build time. So a building that takes 100 seconds to build will in theory also take 100 seconds to repair (from 0 to full health). This time includes conversion duration for example with planetary fortresses.

Strategically speaking, this behavior means that fewer SCVs will be more effective repairing a high HP structure than a low-HP structure against an army of the same DPS. I doubt this would really affect in-game decision making, but maybe it's worth knowing.

Because of the fact that a burning building loses HP while it's burning, you must also calculate this additional time.

So, I think there is no simple answer for your 2nd question. You could figure it out for specific scenarios (e.g. 2 stalkers attacking a bunker) but no general answer would be practical.