How to Do the Math to Cut out 8 Half Square Triangles We have been asked a number of times, how to calculate the size of the starting pieces of fabric when you want to cut 8 Half Square Triangles at the one time. So here it is. We also have a video below on how to cut the 8 half square triangles. Calculation to work out the size of the starting fabric: The size of your finished block + 7/8') x 2 = size of starting fabric For example if you want your finished block to be 2 1/2'
