A MOA, or Minute of Angle, is a unit of measurement used in optics and firearms. One MOA equals 1.047 inches at 100 yards, or 2.094 inches at 200 yards. A scope can be adjusted to be accurate at different ranges by changing the elevation and windage settings. Most scopes have an adjustment range of about 60 MOA, which means that they can be accurate at distances up to about 600 yards.