Quilt border calculator
A 6" border on a 60" x 60" quilt center takes about 1 1/4 yards of fabric and brings the quilt to 72" x 72". Enter your center size and up to three border widths below for cut lengths, strip counts, and yardage for each border.
Finished quilt
How to measure for quilt borders
Here is the secret to borders that lie flat: measure through the middle of the quilt, not along the edges. Edges stretch during piecing and pressing; the center does not lie. Measure the length through the vertical center, cut both side borders to that measurement, and ease the quilt edge to fit the border, never the other way around. Then measure the width through the horizontal center, including the new side borders, and cut the top and bottom to match.
Borders cut to the measured size act like a gentle frame that squares the quilt up. Borders sewn on long and trimmed afterward are how quilts grow wavy edges that no amount of quilting can flatten.
Butted or mitered corners?
Butted corners are the standard: side borders go on first, then top and bottom run straight across. They are fast, sturdy, and right for nearly every quilt. Mitered corners meet at 45 degrees like a picture frame, which is lovely for striped or directional border fabric where you want the print to turn the corner. Miters take longer strips (the calculator adds 4" per strip for the angle) and a bit more patience at the corner seam.
Piecing border strips from width of fabric
Unless your border is shorter than 40", each border strip will be pieced from width of fabric cuts. Join them with diagonal seams pressed open, the same trick used for binding, and the joins all but vanish. The calculator counts the WOF strips you need and converts them to yardage per border, since most quilts use a different fabric for each border.
Sources and methodology
Butted: side borders = 2 strips at the center length; top and bottom = 2 strips at center width + 2 x border width. Mitered: all strips cut at the outer dimension + 4" miter allowance. WOF strips per border = total border inches / usable width (nominal minus 2" for selvages), rounded up; yardage = strips x border width / 36, rounded up to the next quarter yard. Cross-checked against published quilting references before every update.
Border questions, answered
Almost always because the border was sewn on as a long strip and trimmed to fit afterward, which stretches the quilt edge to the border's length. The cure is to cut borders to the quilt's center measurement first and ease the edge in. Pin generously, sew with the border on top, and the waves never form.
A useful rule of thumb: borders look balanced when they are no wider than one block. Many quilts use a narrow inner border (1" to 2" finished) as a frame and a wider outer border (4" to 6") for breathing room. Borders are also the honest way to grow a quilt a size: two borders can take a 70" x 90" twin top to a respectable full.
Lengthwise grain (parallel to the selvage) barely stretches, so borders cut that way are wonderfully stable, but they require buying the full border length in yardage. Crosswise WOF strips are the economical standard and behave well when pieced with diagonal seams and measured properly. This calculator assumes WOF strips; if you splurge on lengthwise borders, buy yardage equal to your longest border length.
Inside out, one complete border at a time: attach border 1 on all four sides, press, re-measure through the center, then attach border 2, and so on. Re-measuring between borders is the step that keeps a three border quilt square; each border is a fresh chance to true things up.