Quilt Blueprint

Quilt backing calculator

How much fabric the back of your quilt needs, and how to piece it.
Quilt size
Width
in
Length
in
Backing fabric width
Extra on each side
in
4 in (10 cm) for a longarm quilter, 2–3 in at home
Backing fabric to buy
3¼

yd

2 widths of 42 in fabric, sewn with one seam running side to side.
How to cut it

2 pieces

Cut 2 pieces 58 in long. The finished back is 58 × 73 in.

How this is worked out

The backing is cut bigger than the quilt top — 4 in on every side is what longarm quilters ask for (2–3 in is enough on a home machine) — because quilting pulls the layers in.
Quilting cotton is about 42 in wide once the selvages are cut off, so most backs are made of two or three widths sewn together. The seams can run up and down the quilt or side to side; the calculator picks whichever needs less fabric. Each backing seam takes ½ in on each side.
Wide backing fabric (108 in) covers most quilts in one piece, with no seam.

Questions

How much backing do I need for a throw quilt?

For a 50 × 65 in throw with 4 in extra on every side: 3¼ yd of 42 in fabric, as two widths of 58 in sewn side to side.

How much backing for a queen quilt?

For a 90 × 95 in queen: 8¼ yd of 42 in fabric (three widths of 98 in), or 2¾ yd of 108 in wide backing.

Should backing seams run vertically or horizontally?

Either works. Horizontal seams often need less fabric on a quilt longer than it is wide; the calculator compares both and tells you which.

Plan the whole quilt

Plan a quilt
Size, block and layout in — every cut, the fabric to buy, backing, binding and batting out.

More calculators

Quilt size chart
Standard quilt sizes from baby to king, in inches and centimetres, and a size for your own bed.
Quilt binding calculator
How many binding strips to cut, and how much fabric that takes.
Quilt batting calculator
Which batting size to buy for your quilt, or how much off the roll.