Fabric Calculator
Free fabric calculator: enter your bolt width and the size and number of pieces you need to get the fabric length and yardage to buy, with the formula shown.
Updated 2026-06-14 · Free · No sign-up · Runs privately in your browser
Show the formula & steps
How the Fabric Calculator Works
This calculator tells you how much fabric to buy when you need several identical pieces — quilt blocks, cushion panels, napkins or garment parts. Enter the fabric bolt width, the number of pieces, and each piece’s width and length. It works out how many pieces fit across the bolt, how many rows you need, and the total length and yardage to purchase.
The Formula
The key insight is that you cut several pieces side by side across the bolt’s width, so the fabric you buy is measured by length:
Pieces per row = floor(bolt width ÷ piece width) Rows needed = ceil(number of pieces ÷ pieces per row) Fabric length = rows × piece length Yards = fabric length ÷ 36
We round down when fitting pieces across the width (a partial piece does not count) and round up the number of rows (you cannot buy a partial row).
Worked Example
You need 8 pieces, each 20 in wide × 18 in long, from a 44 in bolt:
- Pieces per row = floor(44 ÷ 20) = 2 per row
- Rows needed = ceil(8 ÷ 2) = 4 rows
- Fabric length = 4 × 18 = 72 in
- Yards = 72 ÷ 36 = 2 yards
Buying the Right Amount
A few real-world adjustments keep you from running short:
- Seam allowances — if your piece sizes are finished dimensions, add 1/2 in to each edge before calculating.
- Pattern matching — directional prints, stripes and plaids need extra length to align the repeat.
- Shrinkage — pre-washable cottons can shrink 2–5%, so buy roughly 10% extra and pre-wash before cutting.
| Pieces | Piece size | Bolt width | Yards needed |
|---|---|---|---|
| 4 | 18 × 18 in | 44 in | 1.0 yd |
| 8 | 20 × 18 in | 44 in | 2.0 yd |
| 12 | 10 × 10 in | 44 in | 0.83 yd |
Frequently asked questions
How much fabric do I need for my project?+
First find how many pieces fit across the bolt width: divide bolt width by piece width and round down. Then divide the number of pieces by that figure and round up to get the number of rows. Multiply rows by piece length and divide by 36 for yards.
What is a standard fabric bolt width?+
Quilting cotton is usually 42 to 44 in wide, apparel fabrics are often 54 to 60 in, and home decor or upholstery fabric can be 54 in or wider. Always measure the usable width, which excludes the selvage edges.
How do I convert inches of fabric to yards?+
Divide the total length in inches by 36, since one yard equals 36 inches. For example, 90 inches of fabric is 90 ÷ 36 = 2.5 yards. Stores usually cut to the nearest 1/8 or 1/4 yard.
Should I buy extra fabric?+
Yes. Add fabric for seam allowances, pattern or stripe matching, and pre-wash shrinkage, which can be 2 to 5 percent for cotton. A common rule is to buy about 10 percent more than the calculated minimum.
How does cutting layout affect yardage?+
Fitting more pieces across the width reduces the length you buy. A 20 in piece on a 44 in bolt allows two per row, halving the rows needed compared with cutting one piece per row, so wider pieces or narrower fabric use more yardage.