Blooming Baskets Quilt 
Mini Crossbody Bag FREE Pattern/ 
Double Oven Mitt/PDF patterns, and instruction 
Summer Star Quilt 
Evil Eye 🧿 Blue Eye / Nazar, Machine Embroidery Design 4 Sizes 
Honey V Revival Quilt 
How to Sew Half Square Triangles
(The Essential Building Block of Quilting)
@LisaCapenQuilts
@MelanieHam
@ThelittleGreenBean
Step-by-Step Instructions:
Half Square Triangles (HSTs) are one of the most versatile and frequently used units in quilting. The classic “2-at-a-time” method is the standard way to create perfectly accurate squares without handling stretchy bias edges.
Materials Needed:
- Two contrasting fabric squares
- Fabric marking pen or pencil
- Rotary cutter, mat, and square acrylic ruler
- Sewing machine with a 1/4 inch foot
- Iron and pressing mat
Tips for Perfect HSTs:
- Cut your starting squares slightly larger than mathematically required to give yourself “trimming room.”
- Press your seams toward the darker fabric to prevent the seam allowance from showing through the lighter fabric.
- Use a square ruler with a 45-degree diagonal line for perfect trimming.
1. Draw the Diagonal Line
- Place your lighter fabric square wrong side up. Using a ruler and marking pen, draw a straight line diagonally from one corner to the opposite corner.
2. Pair the Squares
- Place the marked lighter square and the darker square right sides together. Align all four raw edges perfectly. Pin if desired to prevent shifting.
3. Sew Both Sides
- Take the paired squares to your machine. Sew a scant 1/4 inch seam down the entire right side of the drawn line. Then, rotate the piece and sew another 1/4 inch seam down the other side of the drawn line.
4. Cut on the Line
- Using your rotary cutter and a ruler, cut the block directly on the center diagonal line you originally drew. This will separate the block into two identical triangles.
5. Press and Trim to Size
- Open the blocks and press the seams flat (usually toward the dark fabric). To trim, lay a square acrylic ruler over the block, aligning the 45-degree diagonal mark on the ruler exactly with your sewn seam. Trim the excess fabric to reach your perfect finished size.
Top FAQs for Half Square Triangles:
What is the formula to cut starting squares for HSTs? +
For the traditional 2-at-a-time method, add exactly 7/8 inch to the finished size of your block. However, many quilters prefer to add a full 1 inch (or even 1 1/4 inch) to give themselves plenty of extra room to trim the block down perfectly after sewing.
Why did my HST end up too small? +
This usually happens because the seam allowance was too wide or the block was skewed during pressing. Always use a “scant” 1/4 inch seam (just a thread width narrower than a true 1/4 inch) to account for the fabric taken up in the fold when pressing.
How do I prevent the bias edge from stretching? +
The 2-at-a-time method prevents stretching because you sew the seam before cutting the bias line. Once cut, be careful not to “iron” back and forth with a heavy hand. Instead, gently press the iron straight down to set the seam without distorting the fabric.
Can I make more than two at a time? +
Yes! There are formulas for 4-at-a-time and the popular “Magic 8” (8-at-a-time) method, which are incredible time-savers if you need a large number of identical Half Square Triangles for your quilt pattern.
