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Piping Calculator — Bias Strip & Cord
Calculate bias strip fabric and cord needed for piping and welting.
How We Calculate This
The bias strip width is calculated from the cord circumference plus seam allowances. The fabric square is sized using the continuous bias method.
The formula
Strip width = (π × Cord diameter ÷ 10) + (2 × Seam allowance)
Cord diameter is in mm, so its circumference is divided by 10 to convert to cm before adding the seam allowance.
Fabric square = √(Piping length in cm × Strip width)
Piping length is in metres, so it is multiplied by 100 to convert to cm before the area is worked out.
Frequently Asked Questions
Small (2–3mm): delicate garments, cushion edges. Medium (4–5mm): standard piping for clothing and soft furnishings. Large (6–10mm): upholstery, statement trims.
For piping that goes around curves, yes — bias cut fabric stretches and moulds around curves smoothly. For straight piping only, you can use straight-grain strips.
Wrap the fabric around the cord and pin. The strip must cover the cord circumference plus two seam allowances (1–1.5cm each side — 1cm/⅜″ is the practical minimum; thinner is hard to sew). Our calculator works this out from the cord diameter.
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Last updated: February 2026
All calculations are estimates. Always verify quantities before cutting or purchasing fabric.