Quarter-square triangle cut plan

Choose a named two- or four-fabric QST construction and starting-square size rule.

Measurements

Editable example inputs. Adjust them for your project.

Finished QST side in Required QST count units

QST construction method

Choose a named construction: paired two-fabric squares yield two units; four-fabric stacks yield four. All listed methods assume 1/4 in seams and trim unfinished units to finished side + 1/2 in. Yardage is not calculated.

Input guidance and units

Enter inches unless a field says otherwise. The result keeps the theoretical quantity separate from purchase rounding.

Enter fractional inches as decimals: 1/8 = 0.125, 1/4 = 0.25, 1/2 = 0.5. Dimensions and yard increments use steps of 0.125; counts use whole numbers. Fraction text such as 1/8 is not accepted in number fields.

What this calculator answers

Quarter-square triangle starting cuts depend on the named construction. This calculator distinguishes paired two-fabric batches from four-fabric stacks.

How to use it

Enter finished QST side and required unit count.
Choose paired two-fabric or four-fabric stack construction.
Choose the extra-trim four-fabric option only when that named starting-size convention is intended.
Cut the stated starting squares per fabric and trim sewn units to the unfinished target.

Formula and variables

Paired two-fabric and standard four-fabric starting side = finished side + 1 1/4 in. The four-fabric extra-trim option uses +1 1/2 in. Batches = ceiling(required units ÷ units per batch). Unfinished target = finished side + 1/2 in.

Constructionmethod: Paired batch uses two fabrics; stack batch uses four.
Starting squaressquares: One square per participating fabric per batch.
Unfinished targetin: Trim size before the unit is joined into the quilt.

Independent example

Seven QSTs with a 4 in finished side using paired two-fabric batches.

Each starting square is 4 + 1.25 = 5.25 in. Four paired batches use four squares from each of two fabrics and produce eight units, one extra. Trim to 4.5 in unfinished.

5.25 in starting squares
4 squares from each fabric
8 units produced
4.5 in unfinished trim target

What the result means

The selected method sets batch yield and starting size. The separate two-square/four-unit variant is not implemented here.

Common questions

Do all QST methods use the same starting size?

No. Select the named paired or four-fabric method; the extra-trim option has a different size addition.

Does this estimate fabric yardage?

No. It counts starting squares and QST units, not WOF strips or yardage.

Method notes and unresolved issues

Use measured usable dimensions and the construction method named on this page. Example inputs are optional and are not universal standards.