Why do fabric widths vary?

Different fabric types are woven on different width looms. Quilting cotton is typically 112cm (44″), dressmaking fabrics 137–150cm, and furnishing fabrics 137cm (54″). Imported fabrics may use different standard widths.

Is the conversion exact?

No — it preserves total fabric area, which is the theoretical minimum. In practice pieces nest less efficiently on a narrower bolt, so add roughly 5–10% (or set the Layout Efficiency Factor to 1.05–1.10). On a narrow width some wide pieces may not fit across at all and would need a seam to split them.

What if my piece is wider than the fabric?

If any single pattern piece is wider than the fabric bolt, you cannot simply convert — you will need to add a seam to split the piece, or choose a wider fabric. This calculator assumes all pieces fit within the bolt width.

SewCalcs

Fabric Width Converter — Convert Between Bolt Widths

Convert fabric requirements between different bolt widths. Perfect for when your fabric is a different width than the pattern specifies.

Original Length

Fabric length at the original width

Original WidthWidth the pattern's yardage assumes

New WidthWidth of your actual fabric

How We Calculate This

The conversion preserves total fabric area using a simple proportion:

The formula

New length = Original length × Original width ÷ New width

Result is rounded up to the nearest 10cm.

Treat it as a minimum

Area conversion gives a theoretical minimum. When you move to a narrower bolt, pattern pieces nest less efficiently, so add roughly 5–10% (set the Layout Efficiency Factor in Advanced Options to 1.05–1.10). Directional or one-way fabrics, large motifs and pieces that must be cut on the fold need a little extra too.

Frequently Asked Questions

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Last updated: February 2026

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