Two-at-a-Time Half-Square Triangles
Before You Begin
Skill Level: Beginner
Technique: Traditional Piecing
Time Required: About 10–15 minutes
Tools Needed: Sewing machine, rotary cutter, quilting ruler, marking pencil, iron, two fabric squares
Introduction
Half-square triangles (HSTs) are one of the most commonly used units in quilting. From classic quilt blocks to modern geometric designs, you'll find them in countless patterns.
The two-at-a-time method creates two identical HSTs from a pair of fabric squares. I prefer making my HSTs slightly oversized and trimming them to their unfinished size for the most accurate results.
Step 1 – Draw the Diagonal Line
Step 2 – Sew Both Sides
Step 3 – Cut Apart
Step 4 – Press
PHOTO
Open each unit and press the seam toward the darker fabric unless your pattern specifies otherwise.
Lift and press the iron rather than sliding it across the fabric to avoid stretching the bias edges.
Step 5 – Trim to Size
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Place a quilting ruler over the HST, aligning the ruler's 45° diagonal line with the sewn seam.
Trim two sides, rotate the unit, then trim the remaining sides until the unit matches the unfinished size listed in your pattern.
My Tip
Don't skip the trimming step. Even experienced quilters can sew seams that vary by a thread or two. Trimming each HST to the correct unfinished size removes those tiny inconsistencies before they become bigger problems during assembly.
Frequently Asked Questions
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A seam allowance that's slightly wider than ¼" is the most common cause. Test your seam allowance before making a full batch.
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Most patterns press toward the darker fabric unless a specific pressing direction is given.
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If your pattern recommends trimming, I do. Consistently sized units make the rest of your quilt much easier to assemble.
Continue Learning
Accurate Quarter-Inch Seam Allowance
Eight-at-a-Time Half-Square Triangles
Square-in-a-Square
No-Waste Flying Geese
