Quilt math · Sizes and yardage
Width of fabric (WOF) explained
WOF turns up in every cutting list. Here’s what it means, how wide your fabric really is, and what the selvages have to do with it.
The short answer
WOF means width of fabric: across the fabric from selvage to selvage. Quilting cotton is usually 42″ to 44″ wide, and about 40″ to 42″ once you trim the selvages. Wide backing is 108″.
What WOF means
WOF is short for width of fabric: the distance across the fabric from one selvage to the other, as it comes off the bolt. A pattern that says “cut 3 strips 2½″ × WOF” means three strips 2½″ wide, cut across the fabric from selvage to selvage.
Quilting cotton is mostly 42″ to 44″ wide on the bolt. Some is narrower, around 40″, and wide backing is 108″. The label on the bolt end says, but it’s worth measuring: a fabric sold as 44″ is often a little less once it’s washed.
Selvages, and why we trim 2″
The selvages are the finished edges along both sides of the fabric, often printed with the maker’s name and color dots. They’re woven tighter than the rest, so they don’t shrink or stretch the same way. Left in a seam, they can pucker it.
So we trim them off before seaming a backing: about 1″ each side, 2″ in all. Where a pattern cuts strips across the whole width, the selvages come off the strip ends instead.
| On the bolt | Left to sew | Throw backing (60″ × 72″ top) | King backing (108″ × 108″ top) |
|---|---|---|---|
| 40″ | 38″ | 4½ yd, 2 widths | 13 yd, 4 widths |
| 42″ | 40″ | 4½ yd, 2 widths | 9¾ yd, 3 widths |
| 44″ | 42″ | 3⅞ yd, 2 widths | 9¾ yd, 3 widths |
| 108″ | 106″ | 2 yd, one piece | 6½ yd, 2 widths |
A yard is 36″ whatever the width, so it gives 14 strips of 2½″. What changes with the width is how long each strip is, and how many widths a backing needs.
Lengthwise, crosswise and bias
- Lengthwise grain runs along the selvages. It barely stretches: good for long borders and sashing.
- Crosswise grain runs across the width, selvage to selvage. It has a little give. Most strips are cut this way (WOF strips).
- Bias runs at 45° to both. It stretches the most: handle bias edges, like a triangle’s long side, gently.
108″ wide backing
Wide backing is made for the back of a quilt: 108″ on the bolt, 106″ once the selvages are trimmed. Up to that size one way, the whole back is one piece with no seam. The backing calculator compares it with seaming ordinary fabric.
Patterns and WOF. Most patterns work their yardage for 40″ to 42″ of usable width. If your fabric is narrower, or you pre-wash and it shrinks, check strip counts before you cut. See shrinkage and pre-washing.
A fat quarter is cut differently: a quarter yard cut wider, so it’s squarer. See fat quarter sizes.
Questions
Short answers.
Something else? A real person replies.
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What does WOF mean in quilting?
Width of fabric: the distance from selvage to selvage. “Cut 3 strips × WOF” means strips cut all the way across the fabric.
How wide is quilting cotton?
Usually 42″ to 44″ on the bolt, sometimes around 40″. Measure yours, and remember it shrinks a little if you pre-wash.
Should I cut off the selvages?
Yes, before you sew. They’re woven tighter and can pucker a seam. We allow 2″ in all, about 1″ each side.
What is LOF?
Length of fabric: along the selvages, the lengthwise grain. Long borders are often cut this way, because it barely stretches.