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Quilt Border Calculator

Enter your quilt size, border cut width, and number of layers to get exact strip count, yardage to buy, and finished quilt dimensions after borders.

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Your results

Yardage to buy5/8 yd
Cutting instructionCut 7 strips at 3″ × WOF.
Total strips7
Finished quilt size65″ × 85″

How the border yardage calculation works

Border strips are cut width-of-fabric (WOF) — from selvedge to selvedge at 42 to 44 inches — and joined end-to-end to reach the length of each quilt edge. To find the total length of strip needed, the calculator adds all four sides of the quilt together plus a 10-inch safety margin for diagonal joining seams and minor cutting variances. It then divides by the fabric width to get the number of strips, and multiplies by the border cut width to get total fabric inches.

For quilts with more than one border layer, the calculation runs iteratively. After the first border is applied, the quilt grows by twice the finished border width in each direction. That larger size is used as the input for the second layer, and so on. This is why the total strip count is not simply the number of layers times the first-layer strip count — each successive layer needs slightly more length than the last.

Butted vs. mitered corners

Most quilts use butted corners: attach the two side borders first, then attach the top and bottom borders across the ends. Simple, fast, and this calculator is built for it.

Mitered corners require each border strip to extend past the quilt corner by the border width, then be trimmed and sewn at a 45° angle. They look elegant on striped or directional prints where continuity around the corner matters. To estimate yardage for mitered corners, add approximately two border widths to the required strip length per strip — or simply add 20–25% to the yardage this calculator gives you.

Worked examples

These calculations use the defaults: 42″ fabric width, ¼″ seam allowance, butted corners.

Quilt sizeBorder cut widthLayersStripsYardageFinished size
36″ × 50″2″153/8 yd39″ × 53″
60″ × 80″3″175/8 yd65″ × 85″
90″ × 108″4″1101 1/8 yd97″ × 115″
60″ × 80″2″2157/8 yd66″ × 86″
108″ × 108″3″1111 yd113″ × 113″

The two-layer example (row 4) shows how the second border layer needs more strips than the first because it surrounds a larger quilt. Always re-run the calculator rather than doubling the first-layer figure.

Tips for accurate border attachment

  • Measure through the centre, not the edges. Quilt edges stretch more than the centre during assembly. Measure the quilt through the middle in both directions and cut the border strips to those measurements — do not measure the edge itself.
  • Mark the midpoints. Fold each border strip and quilt edge in half and mark the midpoints with a pin. Match midpoints first, then the ends, then ease the fabric evenly between. This prevents wavy borders.
  • Attach side borders before top and bottom. Standard butted-corner order. Sew the two long side borders first, press, then measure again through the centre for the top and bottom lengths.
  • Press seams toward the border. Border seams usually press toward the border fabric (away from the quilt centre) to reduce bulk and keep the quilt top flat for quilting.
  • Let the quilt rest before measuring. After washing and pressing, let your quilt top relax flat for 10–15 minutes before measuring for the border. Pressing can temporarily distort dimensions.

Frequently Asked Questions

What is the difference between butted and mitered border corners?
Butted borders are the most common style — side borders are sewn on first, then top and bottom borders are sewn across the ends, creating right-angle joins. Mitered borders meet at a 45° angle in each corner, like a picture frame. Mitered corners look more polished but require longer strips: each strip must extend past the quilt edge by approximately twice the border width. This calculator uses butted corners. For mitered borders, add roughly two border widths to each strip length when estimating yardage.
Why does the calculator add 10 inches to the strip length?
The 10-inch safety margin covers three things: the small amount of length lost to each diagonal joining seam when strips are sewn end-to-end; minor cutting inaccuracies on the quilt edge; and a small play allowance for squaring up the quilt top before attaching borders. For very large quilts — king-size and above — measure your actual cut strips against the quilt edges before trimming to confirm the margin is sufficient.
Which direction do border strips run — along the grain or cross-grain?
This calculator assumes cross-grain strips cut from selvedge to selvedge (width of fabric, WOF), joined end-to-end with diagonal seams. Cross-grain is the standard approach and uses the least fabric. Some quilters cut borders lengthwise along the grain for more stability and to avoid seams — especially for wide borders or when the border print needs to run in one direction. Lengthwise cuts require significantly more yardage because each strip consumes the full length of the quilt.
Do I enter the finished border width or the cut width?
Enter the cut width — the width you will actually cut the strip before sewing. For a border that should finish at 3″, enter 3.5″ as the border width (3″ + ¼″ seam allowance on each side). The seam allowance field (default ¼″) tells the calculator how much of the strip disappears into the seam, so it can correctly track how the quilt grows after each layer when you use multiple borders.
What if I want each border layer in a different fabric?
Run the calculator once per fabric. For the first border, enter your quilt dimensions and 1 for number of layers — note the yardage. Then enter the finished dimensions from those results as the new quilt dimensions and run again for the second border. Alternatively, enter all layers at once (same fabric) to get the total strip count, then split that count manually between your chosen fabrics.

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