Fabric Calculator
Enter your project dimensions, fabric width, and a few options to find out exactly how many yards or metres of fabric to buy. The calculator accounts for seam allowances, pattern repeats, and a waste buffer so you never run short at the cutting table. Switch between imperial (inches, yards) and metric (centimetres, metres) at any time.
How the fabric calculator works
The calculator divides the fabric bolt width by the width of each cut piece to find how many pieces fit side by side in a single row. It then divides the total number of pieces by that pieces-per-row figure to find how many rows of cuts run along the length of the bolt. Rows multiplied by the cut length gives the raw length in inches or centimetres. The calculator then adds extra for pattern repeat alignment (if needed) and multiplies by the waste factor, then converts to yards or metres and rounds up to the nearest 0.25 purchase increment. Adding the seam allowance to each dimension before layout is what keeps the finished piece the right size after stitching.
Seam allowance and cut size
A seam allowance is the strip of fabric between the cut edge and the stitch line. Most commercial patterns use 5/8" (1.6 cm), while quilters tend to use 1/4" (0.6 cm). This calculator adds the seam allowance to both the width and the length of each piece before computing the layout, so the finished piece will be exactly the size you entered after sewing. If you are cutting without seam allowances, for example for applique or iron-on pieces, set the seam allowance to zero.
Pattern repeat and directional fabrics
A pattern repeat is the vertical distance between identical motifs on a printed or woven fabric. When cutting multiple pieces, each new row must start at the same point in the repeat so the design lines up across finished panels or quilt blocks. The calculator finds how much of the repeat remains after each cut length and adds that gap to subsequent rows. Horizontal stripe and plaid matching is not included here, but as a rule of thumb add one full repeat per seam in that direction. Solid, textured, and non-directional fabrics can leave pattern repeat at zero.
Curtain fullness and gather ratios
Curtain fullness describes how much extra fabric is gathered into the finished width. A flat panel uses 1:1 fullness, which means the cut width equals the rod width. A standard gathered curtain uses 2:1, so the fabric is twice as wide as the finished panel. Pinch-pleat and pencil-pleat headings can go up to 2.5:1 or 3:1. The calculator multiplies your panel width by the fullness ratio before working out how many pieces fit across the bolt, so the yardage already accounts for the gathering. Add a hem allowance by including it in your piece length.
Waste factor and shrinkage
Most fabrics shrink when washed. Cotton and linen can shrink 3-5%, wool up to 10%, and some loosely woven fabrics even more. A 10% waste buffer covers typical shrinkage plus normal cutting waste. Raise it to 15% for directional prints, plaids, or stripes that require matching, and to 20% for expensive or hard-to-replace fabrics where mistakes are costly. Beginners should also add at least 10-15% until they are comfortable with their cutting accuracy. Always pre-wash fabric before cutting.
Common fabric bolt widths
| Width (inches) | Width (cm) | Best for |
|---|---|---|
| 36" | 91 cm | Quilting cotton, craft fabric, muslin |
| 44-45" | 112-114 cm | Apparel cotton, linen, shirting |
| 54" | 137 cm | Home decor, upholstery, medium-weight fabrics |
| 60" | 152 cm | Knits, fleece, wide apparel fabric |
| 72" | 183 cm | Felt, fleece, wide home decor fabric |
Standard bolt widths you will find in most fabric stores. The wider the bolt, the more pieces fit in a single row.
Frequently asked questions
How do I calculate how much fabric I need?
Find the cut dimensions of each piece (finished size plus seam allowances on all sides). Divide the fabric bolt width by the cut piece width to find pieces per row. Divide total pieces by pieces per row (rounding up) to get the number of rows. Multiply rows by the cut length. Add extra for pattern repeats and a waste buffer of at least 10%. Convert the total to yards or metres and round up to the next 0.25.
What fabric width should I choose?
Check the bolt label at the store, or the product listing online. Common widths are 44-45" (quilting cotton), 54" (home decor), and 60" (knits and many apparel fabrics). A wider bolt means more pieces fit in a single row, which lowers the total length you need to buy.
Do I need to add seam allowances to the measurements I enter?
No. Enter the finished (sewn) dimensions and pick your seam allowance from the dropdown. The calculator adds the allowance to both the width and length before working out the layout, so the finished piece matches what you entered.
What is a pattern repeat and when does it matter?
A pattern repeat is the vertical distance between identical points in the fabric design. It matters any time you want the motif to line up between panels, cushion fronts, or quilt blocks. Enter the repeat length and the calculator adds extra fabric at each new row to keep the design in register. Leave it at zero for solid, textured, or non-directional fabrics.
How much extra fabric should I buy for shrinkage?
A 10% waste buffer covers shrinkage and routine cutting errors for most projects. Add 15% for directional or patterned fabric, and 20% for complex layouts or expensive fabrics. Always pre-wash before cutting to release shrinkage before you measure and cut your pieces.
How do I calculate fabric for curtains?
Measure the finished width of the curtain track or rod and the drop from the top of the curtain to the hem. Enter those as piece width and piece length, set the number of panels, choose your fullness ratio (2x is standard for gathered curtains), and include a hem allowance in the length. The calculator multiplies the panel width by the fullness ratio before fitting pieces across the bolt.
Can I use this for quilts?
Yes. Enter the cut size of a single quilt block (or strip), set the quantity to the total number of that piece in the quilt, choose your seam allowance (quilters usually use 1/4"), and set pattern repeat to zero for solid or low-volume prints. Run a separate calculation for each fabric in the quilt.