What is the two-at-a-time HST method?
Cut two squares, draw a diagonal line, sew 1/4 inch on each side, and cut on the line. This gives two HSTs from one pair of squares.
Free quilting calculator
Half-Square Triangle Calculator
Half-square triangles are one of the most used quilt blocks. This calculator tells you the cut square size and yardage needed for your planned finished HST size.
Result
HST cutting estimate
Cut 48 squares at 5.25" to make 48 HSTs.
- Finished HST size
- 4"
- Cut square size
- 5.25"
- Squares to cut
- 48
- Squares per row (WOF)
- 8
- Rows needed
- 6
- Estimated yardage
- 0.875 yards
Two-at-a-time method: cut squares in pairs, draw a diagonal line, sew 1/4 inch on each side, cut apart for two HSTs.
Formula
Two-at-a-time cut size = finished size + 1.25 inches. Traditional cut size = finished size + 0.875 inches. Yardage is estimated from WOF rows.
Example calculation
For a 4 inch finished HST using the two-at-a-time method, cut squares at 5.25 inches.
Results are planning estimates. Always round up when buying fabric, especially for directional prints, shrinkage, fussy cutting, or cutting mistakes.
Related calculators
Quilt Block CalculatorCalculate how many quilt blocks you need based on finished quilt size, block size, sashing, and borders.Fabric Yardage CalculatorEstimate fabric yardage from piece size, fabric width, quantity, seam allowance, and project type.Flying Geese CalculatorCalculate sky square and geese rectangle cutting sizes plus fabric yardage for flying geese quilt blocks.
Frequently asked questions
Should I trim HSTs after sewing?
Yes. Most quilters trim to the exact finished size for accurate piecing.
Does this include four-at-a-time HSTs?
No. The four-at-a-time method uses a different formula and is not included in this version.
What seam allowance is used?
A standard 1/4 inch seam allowance is used in all calculations.