What this calculator does
A border frames the pieced center of a quilt and is the cheapest way to make a quilt bigger. The math is simple but easy to get wrong in the shop: the top and bottom borders are longer than the quilt is wide because they also cover the ends of the side borders, and the cut width needs a seam allowance on both edges.
This calculator gives you every number in one place: how wide to cut the strips, how many width-of-fabric strips that takes, how long to cut each border, and how big the quilt will be when you are done.
How to use it
- Measure your quilt center vertically and horizontally through the middle, not along the edges.
- Enter the finished border width you want. A 4 inch finished border is cut 4½ inches wide.
- Cut the strips, sew them end to end, then cut the side and top/bottom lengths from that long strip.
- Pin each border at the ends and the middle before sewing, easing any fullness.
The math
cut width = finished width + ½″
side borders = 2 × center length
top and bottom = 2 × (center width + 2 × finished width)
strips = round up (total length ÷ usable width)
Example: a 48 × 60 inch center with 4 inch borders. Cut strips 4.5″ wide. The sides need 2 × 60 = 120 inches and the top and bottom 2 × 56 = 112 inches, so 232 inches in all. That is 6 strips, or 3/4 yd. The finished quilt is 56 × 68 inches.
Several borders?
Run the calculator once per border. For the second border, enter the size of the quilt with the first border on (the "Quilt with borders" number in the result). That way every border is cut to the true size of what it is being sewn to.
Directional prints and stripes. A striped border cut across the width runs the opposite way on the sides and the top. If that bothers you, cut the sides lengthwise or choose a non-directional print.
Once the borders are on, use the final size in the binding calculator.
Questions people ask
Why measure through the middle of the quilt?
The edges of a pieced top stretch as you handle it, so they are often longer than the center. Cutting borders to the center measurement and easing the edge to fit keeps the quilt square and stops wavy borders.
Should I sew the sides or the top and bottom first?
Either works, but be consistent. This calculator adds the side borders first, so the top and bottom borders are as long as the width plus both side borders. Many patterns do it this way.
How do I calculate mitered borders?
For a mitered corner each strip must run past the corner by the border width plus a couple of inches. Add 2 × the border width plus about 4 inches to the length of every strip. This calculator gives straight (butted) borders.
Can I cut borders along the length of the fabric instead?
Yes, lengthwise-grain borders need no joins and stretch less. You need a piece of fabric as long as your longest border, which usually means more yardage, but the leftover is a long useful piece.