Cutting sizes to make half-square triangles (HST) at a finished size.
The 2-at-a-time method adds 7/8\u2033; the 8-at-a-time method uses one large square.
A half square triangle is a square made of two triangles joined along the diagonal. The easiest method to make them is to sew two squares together and cut them apart, which gives two units at a time. The squares are cut seven eighths of an inch larger than the finished size, so a 3 inch finished triangle square is cut from 3.875 inch squares.
Draw a line diagonally on the back of the lighter square, sew a quarter inch from each side of the line, cut on the line, and press the seam open or toward the darker fabric. Each pair of squares produces two matching units.
Some quilters cut the squares an inch larger and trim the units down to the exact size, which wastes a little fabric but gives accurate, crisp results. The trimmed units are very precise and make later piecing easier.
Half square triangles are used in many designs, including pinwheels, stars, and flying geese variations, so it is worth practicing until the points are sharp. Press carefully, since stretching the bias edges can distort the squares.