You all thought I forgot about this, didn't you? Well I didn't. I just procrastinated for like 5 months. Also got to get around to doing the other giants in League of Legends...
Once again, this is based on Xiaorobear's height chart for the units, which is official except for the Liberator, which literally didn't exist when Blizzard asked him to make it, but that doesn't matter this time.
Conversion Factor[]
The conversion factor should be the same as in the other calc due to using the same picture, but I'll post it down here as well.
For this, I will assume that the Spectre is your average 5 feet 10 inches, or 1.778 meters, tall male.
The Spectre is 64 pixels tall.
1.778 meters / 64 pixels = 0.02778125 meters/pixel.
In the space scene, we are given a pixels to kilometers conversion. The bar is 500 pixels long, and a kilometer is 1000 meters.
1000 meters / 500 pixels = 2 meters/pixel.
However, for this, there is one last part of the picture, way down at the bottom, that we have to consider because it gives us the full length view of a leviathan. While it doesn't fully measure the leviathan, rather saving that for the Spear of Adun because who the hell would want to fully draw a 72 kilometer long spacecraft made of a bunch of floating parts? It does however give us the distance of 1 kilometer in this scene, like in the space scene, so we can use it to scale.
The pixels-to-kilometer bar is 123 pixels long.
1000 meters / 123 pixels = 8.1300813... meters/pixel.
Unit Heights[]
EDIT: Well the pictures won't be coming for a while because Paint screwed up. Dammit Paint. Why do you have to suck?
I'll mostly be excluding "body fluff" from the measurements, AKA horns or spikes.
Larva: Height: 6 pixels or 0.16668750 meters, Length: 36 pixels or 1.00012500 meters.
Zergling: Height: 38 pixels or 1.05568750 meters, Length: 94 pixels or 2.61143750 meters.
Baneling: Height: 67 pixels or 1.86134375 meters, Length: 88 pixels or 2.44475000 meters.
Roach: Height: 79 pixels or 2.19471875 meters, Length: 109 pixels or 3.02815625 meters.
Defiler: Height: 74 pixels or 2.08359375 meters, Length: 414 pixels or 11.50143750.
Drone: Height: 46 pixels or 1.27793750 meters, Length: 124 pixels or 3.44487500 meters. NOTE: May be off because its tail curves up for some reason, even though they never do this in game if I remember correctly. Xiarobear must have been Amon the whole time.
Hydralisk: Height: 132 pixels or 3.66712500 meters, Length: 224 pixels or 6.22300000 meters.
Queen: Height: 166 pixels or 4.61168750 meters, Length: 159 pixels or 4.41721875 meters.
Infestor: Height: 170 pixels or 4.72281250 meters, Length: 259 pixels or 7.19534375 meters.
Lurker: Height: 248 pixels or 6.88975000 meters, Length: 366 pixels or 10.16793750 meters.
Ravager: Height: 224 pixels or 6.22300000 meters, Length: 239 pixels or 6.63971875 meters.
Swarm Host: Height: 401 pixels or 11.14028125 meters, Length: 487 pixels or 13.52946875 meters.
Ultralisk: Height: 816 pixels or 22.66950000 meters, Length: 838 pixels or 23.28068750 meters.
Overlord: Height: 462 pixels or 12.83493750 meters, Length: 679 pixels or 18.86346875 meters.
Overseer: Height: 369 pixels or 10.25128125 meters, Length: 549 pixels or 15.25190625 meters.
Brood War Queen: Height: 163 pixels or 4.52834375 meters, Length: 185 pixels or 5.13953125 meters.
Scourge: Height: 131 pixels or 3.63934375 meters, Length: 149 pixels or 4.13940625 meters.
Mutalisk: Height: 209 pixels or 5.80628125 meters, Length: 127 pixels or 3.52821875 meters.
Guardian: Height: 223 pixels or 6.19521875 meters, Length: 465 pixels or 12.91828125 meters.
Corruptor: Height: 197 pixels or 5.47290625 meters, Length: 288 pixels or 8.00100000 meters.
Brood Lord: Height: 215 pixels or 5.97296875 meters, Length: 1213 pixels or 33.69865625 meters.
Broodling: Height: 30 pixels or 0.83343750 meters, Length: 107 pixels or 2.97259375 meters.
Viper: Height: 98 pixels or 2.72256250 meters, Length: 750 pixels or 20.83593750 meters.
Leviathan: Height: 412 pixels or 3349.59349560 meters, Length: 1331 pixels or 10821.13821030 meters.
Potential Scaling[]
Alright, since I know from the Thor that blowing the Ultralisk up wouldn't result in anything interesting, lets go straight to the Leviathan.
(976/2/4.8)ˆ3*0.005 = 7161024.13086344 tons of tnt, City level.
Final Notes[]
Unfortunately the Leviathan already scales from Kerrigan and other heroes, so the potential durability can't be applied unless they're downgraded for whatever reason. Still dunno if that's how Durability Via Size works anyway, so whatever.
Seriously though how do Marines kill half of these units?