Given that I’m doing a bag making tutorial once a month, I thought I’d also listen to my quilt making readers and give them a tutorial too.
Half Square Triangles (HSTs): The Basics
Half square triangles, or HSTs, are one of the most commonly used units in quilt blocks after plain squares. Here are four popular methods to create them:
Method 1: Sew Cut Triangles
- Cut each fabric into right triangles.
- Place triangle pairs right sides together and sew along the long (bias) edge.
- Use starch to stabilize the bias and reduce stretching.
Method 2: Two Squares → Two HSTs
- Place two same-size squares right sides together.
- Draw a diagonal line corner to corner.
- Sew a ¼″ seam on both sides of the line.
- Cut on the center line, open, press, and trim.
Method 3: Two Squares → Four HSTs
- Stack two identical squares right sides together.
- Sew a ¼″ seam all around the square, pivoting at each corner.
- Cut on both diagonals, open each unit, press, and trim.
- Note: You’ll still have bias edges when joining units, so starching is recommended.
Method 4: Two Squares → Eight HSTs
- Stack two same-sized squares right sides together.
- Draw both diagonal lines on the top square.
- Sew a ¼″ seam on both sides of each diagonal.
- Cut along the drawn diagonals and between them, open units, press, and trim.
- No exposed bias when assembling—ideal for speed and accuracy!
Choosing Your Favorite
Most quilters rarely need completely unique HSTs, so Methods 2–4 will speed up your piecing. Personally, I favor Method 2 because it balances simplicity, precision, and minimized bias edge handling. But feel free to pick the one that suits your project!
Cutting Chart for HST Methods
Note: For Method 1, cut your triangles from squares sized the same as in Method 2. Method 3 values are rounded to the nearest 1/8″.
| Finished HST Unit | 2-to-2 Method Starting Square |
2-to-4 Method Starting Square |
2-to-8 Method Starting Square |
|---|---|---|---|
| 2″ | 2 ⅞″ | 3 ⅜″ | 5 ¾″ |
| 2 ½″ | 3 ⅜″ | 4 ⅛″ | 6 ¾″ |
| 3″ | 3 ⅞″ | 4 ¾″ | 7 ¾″ |
| 3 ½″ | 4 ⅜″ | 5 ½″ | 8 ¾″ |
| 4″ | 4 ⅞″ | 6 ¼″ | 9 ¾″ |
| 4 ½″ | 5 ⅜″ | 6 ⅞″ | 10 ¾″ |
| 5″ | 5 ⅞″ | 7 ⅝″ | 11 ¾″ |
| 5 ½″ | 6 ⅜″ | 8 ⅜″ | 12 ¾″ |
| 6″ | 6 ⅞″ | 9″ | 13 ¾″ |
| 6 ½″ | 7 ⅜″ | 9 ¾″ | 14 ¾″ |
| 7″ | 7 ⅞″ | 10 ½″ | 15 ¾″ |
| 7 ½″ | 8 ⅜″ | 11 ⅛″ | 16 ¾″ |
| 8″ | 8 ⅞″ | 11 ⅞″ | 17 ¾″ |
Happy HST-ing!
