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Finished piece to cut size

Add an explicit seam allowance to a finished square or rectangular quilt piece.

Measurements

Editable example inputs. Adjust them for your project.

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

Finished dimensions describe the piece after it is sewn into the project. A cut rectangle includes seam allowance on both opposing edges.

How to use it

  1. Enter finished width and length.
  2. Enter seam allowance per edge, not total allowance for a dimension.
  3. Calculate and use the displayed cut width and length.

Formula and variables

Cut width = finished width + 2 × seam allowance per edge. Cut length = finished length + 2 × seam allowance per edge.

Finished dimensionin
Target size after the piece is sewn into the quilt.
Seam allowance per edgein per edge
Allowance added independently to each outer edge.
Total addedin
Twice the per-edge allowance on one dimension.

Independent example

6 × 8 in finished rectangle with a 1/4 in seam allowance on every edge.

Each dimension gains 2 × 0.25 = 0.5 in. Cut size = 6.5 × 8.5 in.

  • 6.5 in cut width
  • 8.5 in cut length

What the result means

This is a rectangular-piece seam calculation, not a triangle-unit sizing rule or a fabric yardage estimate.

Common questions

Is the seam allowance per side or total?

Enter the allowance at one edge; the calculation adds it twice to each dimension.

Does this calculate yardage?

No. It returns one square or rectangle cut size.

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.

Continue with the method

Keep the next decision close to the calculation.

Sashing and cornerstone plan Generate rectangular sashing and cornerstone cuts from block layout dimensions. Quilt-top yardage from a cut list Estimate quilt-top yardage from multiple rectangular cut sizes, grouped by fabric. Two-at-a-time HST cut plan Plan paired starting squares for half-square triangle units with the standard two-at-a-time sizing method. Quilting fractions and yardage Look up decimal inches and linear yardage conversions without changing a cut plan. Fabric and cutting labels Print blank tags to keep fabric IDs, cut sizes and quantities together.