What this calculator does
A fabric calculator answers one practical question before a trip to the shop: how many metres of fabric to buy. Enter the size of the piece or pieces the project needs, the width of the fabric bolt on offer, and how many pieces are required, and it works out how many rows of pieces fit down the length of the bolt and how long a cut that adds up to.
This is a general starting estimate for a simple rectangular layout, not a substitute for a specific sewing pattern's own yardage requirement. Patterns with curved or angled pieces, directional prints, or nap that has to run one way all use fabric less efficiently than plain rectangles, so their stated yardage is usually higher than this simple grid calculation gives. The wastage allowance is there to cover exactly that gap: set it higher for anything other than plain rectangular pieces.
The formula
The bolt width is divided by the piece width to see how many pieces fit side by side in one row, rounding down since a partial piece cannot be cut. The number of pieces needed is then divided by that row count, rounded up, to get the number of rows required down the length of the fabric. Each row uses one piece length, so total length is rows times piece length, then increased by the wastage percentage to allow for seam takeup, pattern matching, cutting errors and any waste at the edges.
| Term | Meaning |
|---|---|
| Piece width / length | The finished (or pattern) size of one piece to be cut, before allowing for seams. |
| Fabric bolt width | The width of the fabric as sold, commonly 112, 137 or 150 cm for dressmaking and quilting cottons. |
| Wastage / pattern allowance | An editable percentage added on top of the raw length, covering seam allowances, pattern matching, shrinkage and cutting mistakes. |
The inputs explained
| Field | What to enter |
|---|---|
| Piece width (cm) | The width of one piece as it will be cut, including any seam allowance you plan to add. |
| Piece length (cm) | The length of one piece as it will be cut, including any seam allowance. |
| Number of pieces needed | How many identical pieces the project needs in total. |
| Fabric bolt width (cm) | The width of the fabric bolt, as printed on the fabric or bolt label. |
| Wastage / pattern allowance (%) | Extra length to buy on top of the raw calculation. Higher for patterned, directional or curved-cut projects. |
When to use it
Cutting simple panels
Cushion covers, tote bag panels, table runners and similar rectangular pieces fit this calculation closely, since there is little waste beyond seam allowances.
Buying for a patterned or directional fabric
A fabric with a one-way print or a large repeat wastes more material than a plain weave, because pieces cannot be flipped or rotated to fit efficiently. Raising the wastage allowance accounts for this without changing the layout logic.
Comparing bolt widths before buying
The same project can need noticeably different total lengths depending on whether the fabric on offer is 112 cm or 150 cm wide, since a wider bolt often fits more pieces per row.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How much fabric for four 60 by 90 cm panels, at different bolt widths?
The same four panels cut from fabric bolts of different widths.
| Fabric bolt width | Fabric length to buy | Pieces fitting across the fabric width |
|---|---|---|
| 90 cm | 3.96 m | 1 |
| 112 cm | 3.96 m | 1 |
| 137 cm | 1.98 m | 2 |
| 150 cm | 1.98 m | 2 |
| 180 cm | 1.98 m | 3 |
How does the wastage allowance change the total for a set project?
The same layout with the wastage allowance varied.
| Wastage allowance | Fabric length to buy | Length before wastage allowance |
|---|---|---|
| 0% | 1.80 m | 1.80 m |
| 5% | 1.89 m | 1.80 m |
| 10% | 1.98 m | 1.80 m |
| 15% | 2.07 m | 1.80 m |
| 20% | 2.16 m | 1.80 m |
| 25% | 2.25 m | 1.80 m |
Questions
Does this replace the yardage stated on a sewing pattern?
No. This is a general estimate for simple rectangular pieces. A commercial pattern's stated yardage already accounts for its specific pattern pieces, including curves, angles and cutting layout, and should be used instead when one is available.
Why is my fabric shop quoting more than this calculator suggests?
Fabric is usually sold in fixed increments, such as the nearest quarter or half metre, and some shops build in their own margin for cutting variation. Raising the wastage allowance here brings the estimate closer to what is typically recommended.
What wastage allowance should I use for a plain rectangular project?
Around 5 to 10% is usually enough to cover seam allowances and minor cutting error on plain rectangular pieces with no directional print.
How do I handle a directional print or a design that must be railroaded?
Treat the fabric as effectively narrower in the direction the pattern must run, or raise the wastage allowance substantially, since pieces cannot be rotated freely to save fabric the way they can with a plain weave.
For curtain-specific yardage that accounts for fullness and pooling, see the curtain fabric calculator. For cross-stitch projects sized by stitch count, use the cross-stitch fabric calculator.