What size piping cord should I use?

Small (2–3mm): delicate garments, cushion edges. Medium (4–5mm): standard piping for clothing and soft furnishings. Large (6–10mm): upholstery, statement trims.

Does the bias strip have to be on the bias?

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.

How do I calculate the strip width?

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.

SewCalcs

Piping Calculator — Bias Strip & Cord

Calculate bias strip fabric and cord needed for piping and welting.

Piping Length

Finished length of piping needed — measure the seams it edges

Cord Diameter

Cord thickness in mm — 2–3mm cushions, 4–5mm standard, 6–10mm upholstery

Fabric Price (optional)

Cost per metre of fabric, for the cost estimate

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

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Last updated: February 2026

All calculations are estimates. Always verify quantities before cutting or purchasing fabric.