Quilt Border Calculator: Straight Border Fabric and Yardage

Work out straight borders before you cut. Enter your quilt top size, border width and fabric width, and see finished size, strip lengths, strips needed and yardage, with the formula in steps.

Calculate your border

Quilt top width in

Quilt top length in

Border width in

Border width is the finished width of one border, on each side of the top.

Fabric width

Seam allowance for joined strips in

Seam allowance is used only when strips are joined end to end. It is the amount lost at each join.

This calculator works out straight borders only, with square corners. For 45 degree corners, use the Mitered Border Calculator.

Your result

Enter your measurements, then calculate.

How the calculator works

Step 1: Finished size

Finished width equals top width plus 2 times border width. Finished length equals top length plus 2 times border width. Border width is added on each side, so it is counted twice.

Step 2: Strip lengths

Side borders are attached first. Each side strip length equals top length. Top and bottom borders span the full finished width, including side borders. Each top and bottom strip length equals top width plus 2 times border width.

Step 3: Total strip length and strips needed

Total strip length equals 2 times side strip length plus 2 times top and bottom strip length. If total length fits in one fabric width, you need 1 strip. If not, each extra strip adds fabric width minus seam allowance, because seam allowance is lost at each join. Strips are rounded up.

Step 4: Yardage

Fabric length to buy equals strips times cut width. Cut width equals finished border width plus seam allowance on both sides, because each strip loses one seam allowance where it joins the quilt top and one where it joins the next border or binding. Exact yardage equals fabric length divided by 36 in inch mode. Yardage to buy is exact yardage rounded up to the nearest 1/8 yard. In centimetre mode, metres to buy are rounded up to the nearest 0.1 metre. The unit toggle changes all inputs, outputs and rounding together.

Assumptions, shown next to the result

Fabric width is the nominal width. Seam allowance applies at strip joins and at both sides of each strip, which is why cut width is wider than finished border width. No extra is added for cutting mistakes or shrinkage. This calculator is for one straight border. For more than one border, calculate the first border, then use its finished size as the top size for the next border.

Straight borders and mitered borders are different

Straight borders meet at square corners. Mitered borders meet at 45 degree corners, and they need extra length for the miter. Do not use straight border lengths for a mitered border. Use the Mitered Border Calculator for that job.

Yardage chart by quilt size

This chart uses the same formula as the calculator: 4 inch finished border width, 5 inch cut width, 44 inch fabric, 0.5 inch seam allowance, yardage rounded up to the nearest 1/8 yard.

Quilt size	Top size	Finished size	Strips	Yardage to buy
Baby	36 by 48 in	44 by 56 in	5	0.75 yards
Lap	50 by 60 in	58 by 68 in	6	0.88 yards
Twin	68 by 88 in	76 by 96 in	8	1.13 yards
Full	80 by 92 in	88 by 100 in	9	1.25 yards
Queen	90 by 108 in	98 by 116 in	10	1.50 yards
King	108 by 108 in	116 by 116 in	11	1.63 yards

Chart yardage is a guide for the sizes shown. Your exact top size, border width and fabric width may give a different result. Use the calculator above for your own measurements.

Worked example, checked against the calculator

Top size 60 by 72 inches, border width 4 inches, fabric width 44 inches, seam allowance 0.5 inch.

Finished size: width 60 plus 2 times 4 equals 68 inches. Length 72 plus 2 times 4 equals 80 inches.

Side strips: 2 strips, each 72 inches long. Top and bottom strips: 2 strips, each 60 plus 8, which is 68 inches long. Total strip length: 2 times 72 plus 2 times 68 equals 280 inches.

Strips needed: 280 inches does not fit in 44 inches. Each extra strip adds 43.5 inches. Strips equal 1 plus the ceiling of (280 minus 44) divided by 43.5, which is 7 strips.

Fabric length to buy: 7 times 5 inches of cut width equals 35 inches. Cut width equals finished border width 4 inches plus seam allowance 0.5 inch on both sides, which is 5 inches. Exact yardage: 35 divided by 36 equals 0.97 yards. Yardage to buy, rounded up to the nearest 1/8 yard, equals 1.00 yard.

Frequently asked questions

How do I calculate a quilt border?

Add border width to both sides of the quilt top to get finished size. Side borders run the length of the top. Top and bottom borders run the full finished width, including side borders. Add all four strip lengths, work out strips needed from fabric width, and convert strips times cut width to yardage.

How much fabric do I need for a quilt border?

It depends on top size, border width and fabric width. Use the calculator above with your top size, border width and fabric width. The result shows finished size, strip lengths, strips needed and yardage to buy.

What is the difference between straight and mitered borders?

Straight borders meet at square corners, with side borders first and top and bottom borders spanning the full width. Mitered borders meet at 45 degree corners, and they need a different calculation. Use the Mitered Border Calculator for mitered borders.

Do border strips need seam allowance?

Yes, when strips are joined end to end. Each join loses seam allowance from usable strip length. This calculator accounts for seam allowance when it works out how many strips you need, and it adds seam allowance on both sides to get cut width, so the finished border stays at the width you entered.

Can I add more than one border?

Yes. Calculate the first border, then use the finished size from that border as the top size for the next border. Repeat for each border, one at a time.

Why are top and bottom borders longer than side borders?

Because side borders are attached first, they add border width to each side of the top. Top and bottom borders must span that wider width, so they are longer by 2 times border width.

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