Sight-In Calculator
Fired a group and want to know how many clicks to move your sights? Measure how far the center of the group landed from the aim point, and this works out the clicks. It is free.
Want a sheet that shows your group against a grid drawn for your distance and click value? Use the Target Maker.
A one-page reference for reading your group and moving your sights: Sight Adjustment Cheat Sheet ($2.00)