Sorry, I'm not following the significance of the 1/4 and 1/2...
And using inches is actually a modification of the base formula. It requires the additional step of converting inches to yards. Centimeters is can be converted to meters if you're working in metric (European snipers do). I can work in either, it really isn't complicated. Angle is independent of the units of the vertex.
The base formula is:
Range (units) = Size of the object in (units) x 1000 / Size of object in mils
It works with yards or meters:
Range (yards) = Size of the object in (yards) x 1000 / Size of object in mils
Range (meters) = Size of the object in (meters) x 1000 / Size of object in mils
If I wanted to range with the mildots in the field, I wouldn't bother with math anyway. I'd just use a pre-made ranging card like this one:
'
Ranging does require math and knowing the size of your target, correcting for misses does not in a matched FFP setup or in an SFP one (at the magnification the reticle is accurate at). You simply measure with the reticle and plug the numbers into the turrets directly.