Colt is very short. I'd say significantly short.
For the record, Cheetu is about average height.
So even using an average human feels wrong. But I'll give him the benefit of the doubt.
Colt: 1.72m/132px
Youpi: 201px = 2.6m
Well, even with the generous height, that's far from 3 meters. With Colt's actual height, which might be around 1.6m, it would go down to 2.4m, or around what
@Damage3245 calculated, consistency. Inconsistent for you.
Meruem is also a short boi, he's smaller than Pitou, and comparable to this old man Netero who is simply not that tall. I'll be nice and use the average human as well.
Now we
Meruem: 1.72m/186px
Youpi: 332px = 2.8m.
Again, closer to 2.5 than 3.2. Use Meruem's estimated height by the fandom, 1.69m, then we get something closer to 2.7m
"Nah, why did you-", Youpi's feet were bent down.
Again, Meruem, short king.
Meruem is 121 pixels whereas Youpi is 206 pixels, meaning Youpi 1.7x taller than Meruem.
Thus, 1.72m × 1.7x = 2.9m. This, using 1.72m which is generous for Meruem. Using the estimation, we get 2.8m
Knuckle ain't particularly tall either. So a generous 1.75m instead of the average 1.72m should be fine.
(209+318+767+223)÷(276+213+390+90) = 1.56x
1.56×1.75 = 2.7m
Yeah, 2.5m is simply more consistent.