Quilt Border Calculator

Enter your quilt top size and border width to get exact border strip lengths and a fabric estimate — no math, no guesswork.

📖 How it works & FAQ

Quilt top width (in) Quilt top height (in) Finished border width (in) Seam allowance (in) Fabric width (in)

Assumes borders attached to the sides first, then top & bottom.

Cut each strip — wide

2 side borders

Cut length: — each

2 top & bottom borders

Cut length: — each

Total strip length needed: —

Width-of-fabric strips to cut: —

Fabric to buy: —

How border strips are measured

Adding a plain (butted) border to a quilt is a two-step job, and the order changes the math. First you sew a strip down each long side of the quilt top, then you sew strips across the top and bottom — those last two strips now have to span the quilt width plus the two side borders you just added. This calculator follows that sequence, so the numbers you cut actually fit.

The two side strips are cut to your quilt height. The top and bottom strips are cut to your quilt width plus twice the finished border width. Every strip also gets your seam allowance added to its width (both long edges) and length (both ends), so a 4" finished border with a 1/4" seam is cut 4.5" wide.

How the fabric estimate works

Quilting cotton is usually about 42" wide off the bolt. The tool adds up every border strip, divides by that usable width to see how many width-of-fabric strips you must cut, then multiplies by the cut strip width to get the yardage. Long borders that exceed 42" get pieced end to end, which the strip count already accounts for. The result is rounded up to the nearest 1/8 yard so you buy enough.

How to use it

Measure your finished quilt top and enter its width and height in inches.
Enter the finished (visible) border width you want.
Set your seam allowance — 1/4" is standard for quilting.
Confirm the fabric width (42" for most quilting cotton).
Read the cut strip width, the four strip lengths, and the yardage to buy.

FAQ

Do the numbers include seam allowance?: Yes. Both the cut strip width and each strip length already include the seam allowance you enter, so cut exactly what is shown.
Why is the top/bottom strip longer than my quilt width?: Because it spans the quilt plus the two side borders already attached — that adds twice the border width.
Should I buy extra fabric?: The estimate rounds up to the nearest 1/8 yard, but buying a little more is wise if you want to fussy-cut, straighten grain, or handle pieced seams.
Does anything I type get uploaded?: No. Every calculation runs in your browser and nothing leaves your device.

Fabric amounts are estimates for planning — always confirm against your fabric and cutting plan before buying.