What is the difference between bias tape and bias binding?

Bias tape is a general term for a strip of fabric cut at 45 degrees to the grain line. Bias binding specifically refers to tape used to finish raw edges. Both use the same cutting method — the terms are often used interchangeably in UK sewing. This calculator works for both purposes.

How wide should I cut my bias strips?

For single-fold tape, cut strips at twice the desired finished width (e.g., a 12mm finished tape needs 24mm = 2.4cm strips). For double-fold tape, cut at four times the finished width (a 12mm finished tape needs 48mm = 4.8cm strips, which then fold to a finished 12mm). These 2× and 4× ratios match every standard bias-tape-maker tool. This calculator works out the cut width from your finished width and fold type automatically.

What is the continuous bias method?

Rather than cutting individual diagonal strips and joining them by hand, you mark parallel diagonal lines across a fabric square, join two opposite edges with an offset of one strip width, and cut in a spiral. The result is one long continuous strip with minimal hand-sewing of joins. It is the most efficient method for making bias tape in quantity.

How much extra fabric should I allow?

Always build in at least 10% extra for the loss at the start and end of the spiral cut, plus any joins needed for seaming strips together. For small quantities (under 1 metre), allow 15–20% extra as the proportional waste is higher. The waste buffer in Advanced Options adjusts this for you.

Can I use any fabric to make bias tape?

Most woven fabrics work well — cotton lawn and quilting cotton are popular for lightweight tape, while dressmaking cotton suits garment use. Avoid very heavy fabrics as the multiple layers at fold points become bulky. Pre-washing is advisable to prevent finished tape from shrinking after application.

Bias Tape Calculator — Fabric Square Size & Yield

Calculate exactly how much fabric you need to make bias tape, and how much tape a given fabric square will yield.

Desired Tape Length

Total length of bias tape you need to produce, including any overlap for joins

Finished Tape Width

The width of the finished tape once folded and pressed — common UK sizes are 6mm, 12mm and 18mm

Fabric Square Size

The size of the fabric square you intend to use — enter this to see how much tape it will yield

Fold TypeSingle fold shows one raw edge when opened; double fold encases the raw edge completely and is the most common choice for finishing seams and edges

How We Calculate This

The continuous bias method relies on the fact that the total area of all bias strips equals the area of the fabric square.

Key formulae

Cut strip width = Finished width × fold multiplier

Fold multiplier: 2 for single-fold; 4 for double-fold (the strip join seam is taken up in length, not width)

Square side needed = √(Total strip length cm × Cut strip width)

Total yield from a square = (Usable side²) / Cut strip width, where the usable side deducts about 2.5cm (1in) for the tube-forming seam

In the true continuous-bias method the diagonal joins form automatically as you cut the spiral, so there is no separate hand-sewing of strips. The diagonal-pass count is an approximate guide to how many times the cut crosses your square; the waste buffer covers the small loss at the start and end of the spiral.

Frequently Asked Questions

Last updated: March 2026

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

Bias Tape Calculator — Fabric Square Size & Yield

How We Calculate This

Key formulae

Frequently Asked Questions

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