How Much Backing Fabric for a Cal King Quilt?

A California king quilt is 102 inches wide and 100 inches long, so the backing gets cut 110 by 108. That 110 is two inches past the widest bolt of wide backing most shops stock, and those two inches decide how you buy.

Where 110 by 108 Comes From

Backing has to hang past the quilt top so the frame clamps have something to bite. The working default is 4 inches per side. Width is 102 plus 8, or 110 inches. Length is 100 plus 8, or 108 inches. Width is the bigger number here, which is unusual for a bed quilt.

Measure the top you finished first. The 102 by 100 figure assumes a 15 inch drop and a 16 inch foot on a 72 by 84 mattress, and a pillow tuck moves it.

The 42 Inch Route: Three Panels, Nine Yards

Quilting cotton is 44 inches wide and about 42 usable. Two panels reach 84 inches after the seam, and the cut is 110, so this size needs three. Three panels give 126 inches, and 16 inches come off the long edges.

Cut each panel 108 inches long. That is exactly 3 yards, so the order is three 3 yard cuts and the total is 9 yards, a whole number with nothing left over. Sewing the panels the other way, so each runs 110 inches, costs 9.25 yards for a seam that lands crosswise on the back.

Why Wide Backing Stops at This Size

Wide backing is bought by length and clears most beds whole. Not this one. The cut is 110 across the bolt and the bolt is 108, so the fabric has to go on sideways. Rotate it and the bolt width lies along the quilt's 108 inch length while 117 inches of yardage runs across the 110.

The rotated option leaves nothing to trim on the 108 inch axis, so check the bolt before you pay. Some goods sold as 108 measure 107, and 107 fails by an inch.

Cal King Backing by Quilt Top

Tops for this bed run from 92 by 94 up to 108 by 102. All of them need three panels, because every cut width clears 84 inches. The wide column is where the size splits.

Past a 100 inch top width neither cut dimension fits 108, so a seam returns. The 102 by 100 top is the last one that goes on whole, and only because its length is exactly 108.

What Changes at 6 Inches a Side

Longarm quilters usually ask for 6 to 8 inches of overage. At 6 the cut is 114 by 112, so neither dimension fits the bolt width and the rotation trick is gone. Pieced cotton climbs to 9.375 yards, and wide backing needs a seam or a 116 inch bolt, where 3.25 yards still covers the whole back.

Confirm which rule your quilter uses before ordering. The gap is 0.375 yard of cotton and one extra long seam across the back.

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