Half-Square Triangle Calculator

Cut sizes for half-square triangles using the 2-at-a-time and 8-at-a-time methods.

Finished HST size (in) Calculate

How it works

2 at a time: cut two squares at finished size + 7/8 inch, draw a diagonal, sew 1/4 inch either side, cut on the line. 8 at a time: cut two squares at twice that size, draw both diagonals, sew 1/4 inch either side of both lines, then cut horizontally, vertically and on both diagonals. Many quilters add a little extra and trim HSTs down to size for accuracy.

Step-by-step explanation: Half-Square Triangle Cut Sizes Explained

Common sizes, worked out

• What size to cut for 2 inch half-square triangles?
• What size to cut for 2 1/2 inch half-square triangles?
• What size to cut for 3 inch half-square triangles?
• What size to cut for 3 1/2 inch half-square triangles?
• What size to cut for 4 inch half-square triangles?
• What size to cut for 5 inch half-square triangles?
• What size to cut for 6 inch half-square triangles?