The Winchester ballistics calculator is an excellent FREE tool to answer just these questions. it can be used direct online in your PC, or downloaded to your Apple device as an App. Choose your cartridge, sight elevation above bore, zero distance, and presto. Pretty colored lines and charts giving you data to reference at the range. The only down side is that the cartridge selection to choose from is obviously Winchester brand only.
Ballistics | Winchester Ammunition Ballistics Calculator & Ammo Ballistics