Why do I need to convert fabric amounts?

Sewing patterns list fabric requirements for specific bolt widths (e.g., "2.5m of 150cm wide fabric"). If your fabric is a different width, you need more or less length. A narrower fabric needs more length; a wider fabric needs less.

Can I just buy the same length in a different width?

No. If a pattern calls for 2m of 150cm fabric and you buy 2m of 112cm fabric, you may not have enough to lay out all pattern pieces. Always convert using the area method.

Does this work for directional fabrics?

This calculator gives the minimum fabric based on area equivalence. For directional fabrics (one-way prints, nap), you may need 10–15% more than calculated, as pieces cannot be placed in opposite directions.

Should I round up my fabric purchase?

Yes, always round up to at least the nearest 10cm. Fabric shops cut by the metre or half metre, and having a small amount extra is much better than being short.

SewCalcs

Pattern Fabric Calculator — Convert Pattern Requirements

Convert fabric requirements from a sewing pattern when using a different fabric width than specified.

Pattern Fabric Requirement

Length stated on the pattern envelope

Pattern Fabric Width

Width stated on the pattern

Your Fabric Width

Actual width of your chosen fabric

Include wastage allowance

Adds 10% for layout differences

Wastage Percentage

Price Per Metre (optional)

How We Calculate This

This calculator uses the area equivalence method. The total fabric area needed stays the same regardless of bolt width; only the length changes.

The formula

New length = (Original length × Original width) ÷ New width

The wastage percentage is then added to account for differences in piece layout between the two widths. The result is rounded up to the nearest 10cm.

Frequently Asked Questions

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Last updated: February 2026

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