Quilting calculator
Half-Square Triangle Calculator
Size starting squares and batches for 2-, 4-, or 8-at-a-time HST methods.
Free · No account · Editable assumptions
Your result
Recommended answer Calculated resultA value derived from the same validated inputs, assumptions, and calculation contract shown on this page.Learn more
Copies a concise text summary of the current result when browser clipboard access is available.Opens the browser print flow using the dedicated readable plan layout.Transfers the compatible calculated cut requirement into the locally saved project for joint planning.
How this calculator works
Assumptions
Enter the HST’s finished size after it is sewn into the quilt. Trim-friendly mode adds practical squaring room beyond the Standard size. Four-at-a-time construction uses the entered perimeter seam allowance and leaves bias grain on the outer edges.
Methodology
Each method has a fixed yield of 2, 4, or 8 HSTs per batch and its own starting-square formula. The calculator rounds starting sizes as required, rounds batch count upward, and reports both total output and unavoidable extras.
Worked example
To make 24 finished 3-inch HSTs two at a time in trim-friendly mode, cut two 4-inch starting squares for each batch. Twelve batches produce exactly 24 HSTs; square each unit to 3½ inches unfinished.
Limitations
This focused calculator covers the construction method and rectangular measurements described above. It does not infer a complete quilt pattern or replace method-specific instructions.
Common question
Can I change the defaults? Yes. The visible defaults are planning conveniences; use the measurements and assumptions that match your fabric, method, and quilting setup.
Keep planning
Plan more than one piece
Combine all the rectangles for each fabric into a shopping list, cutting list, and visual layout.
Open the fabric cutting plannerTransfers the compatible calculated cut requirement into the locally saved project for joint planning.