There are several methods on creating a flying geese unit.  I use the rectangle and square technique, and the chart below represents measurements for this method.

There are rulers now available to help a quilter make flying geese, but what if you want or need flying geese a certain size, and the ruler is not the right size?

I have found some information and have duplicated it here, to help determine your required finished size, and the rectangle and square size requirements.

I cut strips the size I needed then cut again to the size requirements.  For example for a 2″x4″ unit, I cut a 2½” strip from the rectangle fabric, and cut a 2½” strip from the square fabric.  Then cut the rectangle strip to 2½” x 4½”.  And the Square strip to 2½” x 2½”.

To ensure accuracy it is a good idea to check your unit size, before piecing the units together.  Remember the finished unit size is when piecing is complete.  Otherwise the unit should be the same measurement as the rectangle.