@Incursor
I’m honestly shocked that they’re keeping the height somewhat consistent between generations. Then again, I guess some of the old writing staff is involved, and may have passed the info along. Great to see!

@ThePonyTheorist

This puts Izzy at 44 inches right between the two estimates. Also Izzy is taller than Sunny who average height (per her claim and design notes).

The analysis i’ve done based on the height of a tawny owl suggests that the height of a pony is 45-54 inches. Based on the meter tall candy cane, the height of a pony is 41 or so inches according to common perception.

These ponies are 47 inches tall according to your analysis, which is within a believable scale, maybe a little tall. Nice!

@Background Pony #B055  

 
Is 335 px the length of the vertical line? That line might be shorter than the actual vertical height since we’re viewing this scene at such a skew angle.

@Background Pony #B055  
Also, horse height is not measured to the top of the head. https://www.horse.com/content/horse-care/how-horse-height-is-measured/

@Background Pony #E967  
Maybe ponies have become taller or shorter by this time (average human height has grown throughout history). Maybe the new art style changed their size (CG means it would allow for more consistent sizes than traditional animation).
 
 
@Inkan1969  
@Vengir  
335px divided by 3.89 would give the pony a height of about 86px, smaller than my most conservative estimate even before accounting the pony seems scrunched down. Assuming the 3.89 isn’t the tallest part of the arch would make that worse. I’m not ruling out 3.89 is something other than meters, but until I find another guess/analysis that better fit’s what’s shown…

This is a sequel set in the same universe, they are the same size.

I think that sign says 3.89 pony heights, not meters.

Remember that height clearances under arches are measured at the lowest point under which you expect a vehicle to travel, not the highest point. And even then the unit used might be simply “pony”, possibly equaling to the height of an average earth pony.

Pretty consistent with most G4 estimates, which come up with 3 feet and change.