How to use the fabric yardage calculator
- Enter the fabric width between the selvages, the seam allowance and the extra percent for mistakes and shrinkage.
- List each piece with its name, finished width and length in inches and how many you need.
- Tick One way fabric if the fabric has a nap, stripes or a directional print, so pieces are not turned.
- Read the yards to buy, rounded up to the next eighth of a yard, and the layout of each piece group in the table.
Formula
Cut size = finished size + 2 x seam allowance on each dimension
Pieces across = whole number of cut widths that fit in the fabric width, and rows = quantity / pieces across, rounded up
Length used = rows x cut length, then yards = (total length x (1 + extra %)) / 36
There are 36 inches in a yard. Each piece group is tried both ways around unless the fabric is one way, and the shorter length is kept.
A tote bag from 44 inch fabric
With a 0.5 inch seam allowance and 10 percent extra: two 14 x 16 inch body panels are cut at 15 x 17 inches. Turned so the 17 inch side runs across the fabric, two fit across in a single row of 15 inches. Two 3 x 24 inch straps (cut 4 x 25) stand across in a pair of 4 inch rows, so 8 inches. One 8 x 9 inch pocket (cut 9 x 10) takes 9 inches.
The pieces use 15 + 8 + 9 = 32 inches. Adding 10 percent gives 35.2 inches, which is 0.978 yards, and the tool tells you to buy 1 yard. If the fabric is one way, the body panels take 17 inches, the straps 25 inches and the pocket 10 inches, which is 57.2 inches with extra, or 1.589 yards, rounded up to 1 5/8 yards.
How the layout is worked out
Fabric comes in a roll of a fixed width and any length you buy. To find the length you need, the calculator thinks about each group of identical pieces as a row of pieces placed side by side across the width, repeated down the length. How many pieces fit across the width is the width divided by the cut width, ignoring any fraction. The number of rows is the number of pieces divided by that, rounded up, and each row is as long as the cut length.
Pieces are tried in both directions, because a long thin strap may take much less length when laid across the width. For fabrics with a nap, stripes or a one way print, pieces must point the same way, so turning is switched off. A piece that is wider than the fabric in every allowed direction stops the calculation with a message.
What the extra percent covers
Each piece group is laid out on its own, and rows are never shared between different groups. That keeps the result simple and slightly generous, because in real cutting small pieces can fill leftover space. The extra percent covers mistakes, straightening the grain, shrinkage when you wash the fabric, and matching a pattern. The 10 percent in the form is an example value, so use more for stripes, plaids and large prints that need matching, and less for plain fabric you have cut before.
Round up to the next eighth of a yard because shops sell fabric in cuts of about that size. To convert yards to meters or inches, use the unit converter.
Good to know
Pre-wash fabric if you will wash the finished item, and measure the width after washing because it can shrink. The usable width is usually less than the width on the bolt, because the selvages are not used. If your pattern gives yardage, follow it, because a designer can lay out pieces in ways this simple method does not. For other crafts see the quilt backing and binding calculator, the knitting gauge calculator and the cross stitch size calculator.
Assumptions and limits
- All pieces are rectangles. Curves and angled pieces need a rectangle that encloses them.
- Seam allowance is added on every side of each piece, in inches.
- Each group of identical pieces is laid out alone, and the extra percent is an example value.
- Fabric width is the usable width between the selvages in inches, and the length is bought in eighths of a yard.
Frequently asked questions
How much fabric do I need for a project?
List each piece with its size and quantity, add the seam allowance and fabric width, and the calculator works out the length. It adds a percentage for mistakes and rounds up to the next eighth of a yard.
Why does the calculator turn some pieces?
Turning a piece a quarter turn can fit more pieces across the width and use less length. If your fabric has a nap or a direction, tick One way fabric so no piece is turned.
How much extra fabric should I buy?
The 10 percent in the form is an example. Buy more for fabrics that shrink, for prints that need matching and for first projects, and less for plain fabric you know well.
Does it work for quilts?
It can estimate the total for simple rectangles. For backing and binding there is a dedicated quilt backing and binding calculator.