Question 1

What is the difference between FINISHED, UNFINISHED, and CUT size?

Accepted Answer

FINISHED size is the size of the unit AFTER it is sewn into the quilt — no seam allowance. UNFINISHED (unit) size is the size before it is sewn in, including the ¼″ seam allowance on every edge, so unfinished = finished + ½″. CUT size is the size of the starting fabric squares you cut before sewing.

Question 2

How is a quarter-square triangle made, and why add 1¼″?

Accepted Answer

The traditional QST method starts from two squares. Sew ¼″ on each side of ONE diagonal, cut on that diagonal to get two oversized half-square triangles, then cut each of those on the SECOND diagonal. Each square yields four QST units. The 1¼″ added to the finished size is ⅞″ (the first, HST-style diagonal seam) plus ⅜″ (the second diagonal cut), so starting square = finished + 1¼″ and unfinished = finished + ½″.

Question 3

Why is there only one construction method?

Accepted Answer

Only the traditional method is verified here from authoritative quilting sources. A bulk "16 QSTs at once" method (an 8-at-a-time HST oversized by ⅜″, then halved) is geometrically possible but is not published as a standard, named method by major quilting authorities, so it is intentionally excluded rather than presented with an unverified formula.

Question 4

How is the yardage calculated?

Accepted Answer

Both fabrics need the same number of starting squares, and each square yields four QSTs, so squares per fabric = ceil(QSTs ÷ 4). Squares are laid out across the fabric width: squares across = floor(fabric width ÷ square size); rows = ceil(squares ÷ across); yards = (rows × square size) ÷ 36, rounded up to the next 1/8 yard. The yardage is PER FABRIC — you need this much of each of the two fabrics.

Quarter-Square Triangle (QST) Calculator — Cut Sizes & Yardage

What this calculator determines

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Examples

16 QSTs, 3″ finished

40 QSTs, 4″ finished

8 QSTs, 2″ finished

Assumptions & Conventions

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