Scope rail MOA and elevation travel calculator

How much rail cant (MOA) should your .22 have? Enter your scope's total elevation travel and zero distance. We work out how much up and down adjustment you'll have left once the rifle is zeroed, and how far you can dial without holdover.

Max distance you can dial (no holdover)

For your travel, zero, scope height and load, at each rail cant. Standard atmosphere, no wind; checked to 400 yd.

Rail cant	Zero needs	Down left	Up left	Max dialable range

How it works

The quick rule says: from the scope's optical center you have half the travel each way, and a canted rail adds its cant to the "up" side and takes it from the "down" side. So up = travel ÷ 2 + cant, and down = travel ÷ 2 − cant.

That rule ignores the zero itself. Because the scope sits above the bore, the bore has to point slightly up relative to the scope at your zero distance. With a .22 at 50 yd that takes several MOA of up adjustment. A canted rail supplies some or all of it. If the cant is bigger than what the zero needs, you have to dial down by the difference to zero, and that's what can run you out of down travel.

What we calculate: zero needs Z (in MOA up), found with the same point-mass solver as our ballistics calculator. Down left = travel ÷ 2 − cant + Z. Up left = travel ÷ 2 + cant − Z. Max dialable range is the farthest distance whose drop (relative to your zero) is no more than the up travel left.

Estimates only. Real scopes aren't always centered from the factory (optical-center variance), rails and receivers have tolerances, and ammo varies by lot and barrel. We warn when down travel left is under 5 MOA (1.5 MRAD). Confirm on paper.

Load data

Muzzle velocity and BC as published by each maker (BC treated as G1). Your rifle's velocity will differ.