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Compare backing seam layouts

Compare vertical and horizontal panel layouts using usable width and seam allowance.

Measurements

Editable example inputs. Adjust them for your project.

Optional bolt label only. Enter measured usable width separately; no width is filled or deducted automatically.

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

Compare two uniform rectangular panel directions under the same top size, usable width, overhang and seam assumptions.

How to use it

  1. Enter the quilt top and per-side overhang.
  2. Enter measured usable width and seam allowance.
  3. Allow both directions only when the print permits them; otherwise restrict the direction.
  4. Compare panel count and theoretical yardage for each permitted direction.

Formula and variables

Backing dimensions add 2 × overhang. For each direction, panel count is the smallest n covering the required span after seam take-up: n × usable width − 2 × seam allowance × (n − 1). Theoretical yards = n × cut length ÷ 36.

Required spanin
Backing dimension covered by joined panel widths.
Panel cut lengthin
Opposite backing dimension cut along the bolt.
Seam countseams
Panel count minus one for the uniform layout.

Independent example

60 × 80 in top, 4 in overhang, 40 in usable width and 1/2 in seams.

Target is 68 × 88 in. Vertical: 2 × 88 ÷ 36 = 4.8889 yd. Horizontal: 3 × 68 ÷ 36 = 5.6667 yd. The lower theoretical amount is vertical.

  • 4.889 yd vertical
  • 5.667 yd horizontal
  • Vertical selected

What the result means

The selected direction minimizes theoretical yardage only among the allowed uniform layouts. Directional print constraints take precedence over that comparison.

Common questions

Does this include cutting waste?

Only the allowances named in the inputs are included. The calculation does not infer scrap reuse or an extra waste percentage.

Are the result and purchase amount the same?

Theoretical material required and a recommended purchase quantity are different. A purchase amount is shown only when the method supports it and its rounding choice is supplied.

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.

Quilt backing yardage Plan standard-width backing from explicitly labeled quilt dimensions, overhang, and usable fabric width. Measured backing shrinkage adjustment Convert measured wash-test changes into a prewash backing size without assuming a universal fabric rate. Wide-back fit check Check whether a wide-back fabric can cover the backing in one piece. Quilt backing yardage chart Look up a measured top with explicit width, seam, overhang and purchase assumptions. How to read a quilt backing calculation Understand quilt top size, overhang, usable width, panel count, and purchase rounding.