If you want a walk down the maths involved - check out an app called Strelok (Pro) by Igor Borisov. I have no affiliation with this person or this app, other than I use it for extra-long-distance shooting calculations with a conventional rifle and/or air-rifle shooting calculations.

It's seriously astounding the math and thought that goes into shooting at long range. It makes me realize why I used to miss all the time as a kid; it's not just point and shoot.