How much backing fabric for a throw quilt?

Q: How much backing fabric for a throw quilt?

A 50 x 65 in throw quilt needs a 58 x 73 in backing (4 in extra on every side). With 42 in quilting cotton that is 3 1/4 yd (2 panels, horizontal seams). With 108 in wide-back it is 1 5/8 yd.

Throws are the most common first quilt. At 50 x 65 in they are big enough for the sofa and quick to finish.

3 1/4 yd of 42 in fabric (2 panels, horizontal seam).

1 5/8 yd of 108 in wide-back (no seams).

How it's worked out

Quilt size: 50 x 65 in, which is a typical 50 x 65 in throw (sizes vary by pattern).
Backing size = (50 + 8) x (65 + 8) = 58 x 73 in, which leaves 4 in on every side for the longarm or for basting.
Vertical seams: 2 panels x 73 in = 146 in = 4 1/8 yd.
Horizontal seams: 2 panels x 58 in = 116 in = 3 1/4 yd.
Use the option that needs less: horizontal, 3 1/4 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.