Half-Square Triangle Calculator
Calculate perfect cutting sizes for half-square triangles (HSTs) and determine how much fabric you need. Never waste fabric or end up with the wrong size again!
Calculate Your HSTs
The size of the HST after sewn into your quilt
Visual Guide
Half-Square Triangle
📐 What is an HST?
A half-square triangle is a quilt block made from two triangles sewn together on the diagonal to form a square. It's one of the most common and versatile quilt blocks.
✂️ Traditional Method Steps:
- Cut 2 squares (one of each fabric)
- Draw diagonal line on wrong side of lighter fabric
- Place squares right sides together
- Sew 1/4" on both sides of line
- Cut on drawn line
- Press seam open or to darker fabric
- Trim to size if needed
💡 Pro Tips:
- • Press seams before trimming
- • Use a square ruler to trim accurately
- • Make extras - they're useful for scrappy projects
- • Chain piece for efficiency
Fabric Requirements Calculator
Calculate how much fabric you need to make your HSTs
After removing selvages (usually 2" less)
HST Quick Reference Chart
| Finished Size | Traditional Cut | 4-at-a-Time Cut | 8-at-a-Time Cut |
|---|---|---|---|
| 1" | 10.875" | 2.25" | 4.75" |
| 2" | 20.875" | 3.25" | 7.75" |
| 3" | 30.875" | 4.25" | 10.75" |
| 4" | 40.875" | 5.25" | 13.75" |
| 5" | 50.875" | 6.25" | 16.75" |
| 6" | 60.875" | 7.25" | 19.75" |
💾 Bookmark this page - You'll use it for every quilt project!