Fabric is sold by length off a bolt of fixed width: commonly 44/45 in (112 cm) for quilting cotton and 54–60 in (137–150 cm) for apparel and home décor. Knowing how many pieces fit across the width tells you how many rows you need, and therefore how much to buy.
How to use the Fabric Calculator
- Fabric width
- Piece width
- Piece length
- Number of pieces
- Extra for shrinkage / squaring
Results update as you type, and every field accepts the units shown in its menu.
How it works
Enter the fabric width, the size of each piece and how many you need, plus an allowance for shrinkage and squaring up.
Inputs explained
| Field | What to enter |
|---|---|
| Fabric width | Units: in, cm |
| Piece width | Units: in, cm |
| Piece length | Units: in, cm |
| Number of pieces | A number |
| Extra for shrinkage / squaring | In % |
What each result means
- Pieces across the width = floor([Fabric width]÷[Piece width] + 0.000001)
- Fabric to buy = [Rows down the length]×[Piece length]×(1 + [Extra for shrinkage ÷ squaring]÷100)
- Fabric used efficiently = [Number of pieces]×[Piece width]×[Piece length]÷([Fabric width]×[Rows down the length]×[Piece length])×100
Example values
How the main result changes when Fabric width changes and everything else stays at the example values above:
| Fabric width (in) | Fabric to buy (yd) |
|---|---|
| 22 | 3.67 |
| 33 | 2.57 |
| 44 | 1.83 |
| 55 | 1.47 |
| 66 | 1.47 |
| 88 | 1.1 |
Formula
Pieces across = floor(fabric width ÷ piece width)
Rows = ceil(pieces ÷ pieces across)
Fabric length = rows × piece length (+ extra for shrinkage)
Worked example
Inputs: Fabric width: 44 in; Piece width: 10 in; Piece length: 12 in; Number of pieces: 20; Extra for shrinkage / squaring: 10 %.
Results: Pieces across the width = 4; Rows down the length = 5; Fabric to buy = 1.83 yd; Fabric used efficiently = 91 %.
Frequently asked questions
How much fabric do I need for 20 squares of 10 in?
On 44 in fabric, 4 fit across, so 5 rows × 10 in = 50 in, or about 1½ yards with 10% extra.
Should I pre-wash fabric?
Yes for cotton and linen, which can shrink 3–5%; buy a little extra to allow for it.
How do I convert yards to metres?
1 yd = 0.9144 m.