Half-Square Triangle Paper Template Calculator

Why use paper templates for HSTs?

The traditional 2-at-a-time HST method requires marking a diagonal line on every square of fabric, sewing ¼″ on each side of the line, and often trimming afterward. Paper templates eliminate all three steps — the sewing and cutting lines are pre-printed, and the math is built in so each HST comes out the exact finished size.

This is especially useful when you need a large batch of identical HSTs (bed quilts, star blocks, sampler borders). Print as many copies as you need, pin, sew, and cut. The paper tears away easily after sewing, particularly if you shorten your stitch length to about 1.5.

How the template works

Each template is a grid of square cells. Every cell has one diagonal cutting line (solid) and two parallel sewing lines (dashed), offset ¼″ on each side. Diagonal directions alternate between cells in a checkerboard pattern.

You layer two fabrics right sides together, pin the paper on top, and sew on every dashed line. Then cut on every solid line — the grid lines, the diagonals, and the outer border. Press the seams open, peel off the paper, and each cell yields two finished HSTs.

Tips for best results

• Use a short stitch length (~1.5) so the paper perforates and tears away cleanly.
• Press seams open rather than to one side — it reduces bulk at intersections.
• Starch your fabric before cutting for crisper edges and less bias stretch.
• Verify the 1″ calibration square with a ruler before cutting any fabric.
• Print extras — paper is cheap, and having spares avoids mid-project delays.