Quilt Plan KitHow much backing fabric for a king quilt?
King quilts are wide enough that even 42 in quilting cotton needs three panels for the backing in most layouts.
9 yd of 42 in fabric (3 panels, horizontal seams).
6 yd of 108 in wide-back (no seams needed if you join 2 panels).
How it's worked out
- Quilt size: 100 x 102 in, which is a king mattress (76 x 80 in) with a 12 in drop on both sides and the foot and a 10 in pillow tuck.
- Backing size = (100 + 8) x (102 + 8) = 108 x 110 in, which leaves 4 in on every side for the longarm or for basting.
- Vertical seams: 3 panels x 110 in = 330 in = 9 1/4 yd.
- Horizontal seams: 3 panels x 108 in = 324 in = 9 yd.
- Use the option that needs less: horizontal, 9 yd. Usable width is taken as 42 in (106 in for wide-back).
Open the backing calculator with these numbers, or read how much backing fabric you need.
Planning the whole quilt? The Quilt Planner has a backing and binding worksheet, fabric requirements and a cutting chart for every project.