Mine are all level, but I’d say the back since that’s the part you’re looking at.
Edit to add: from the back your sight is angled which is increasing the distance. I’d think if you can get your calipers perpendicular to the slide you’d have a more accurate measurement.

 

I measure at the aft end of the sight

 

Rear of front sight. But use the other end of your calipers for a more accurate read. The way your measuring there your measuring the angle distance not the straight height. Think of it like a triangle. My guess would be the rear height is about .185-.190

 

These are what I want and prefer. With a square notch rear. Nice three dot alignment.

Sights - Parts for 1911 - Accessories

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So you’re saying from like the side of the slide to the high point of the front right? Straight down?

Like this. Where the red line is.

 

Perpendicular to the slide top. With most semi pistols, it would be at the point closest to you.
With many revolvers, it may be closest to the business end.
The tallest edge of the sight.

 

I also use this end to measure

 

Ohhh duh…
You can tell im not a physicist..🤓

 

The highest point. It's all you'll really see from a proper sight picture.
Jim