How to use this calculator
- Enter or choose length the pattern asks for.
- Enter or choose length in.
- Enter or choose fabric width in the pattern.
- Enter or choose width of your fabric.
- Enter or choose widths in.
- The length needed at your width updates as you type. Use Copy result or Share to keep it.
Method
New length = Original length × Original width ÷ New width
- Original length, width
- what the pattern envelope states
- New width
- the usable width of the fabric you are buying
Worked example
- Area = 2.5 yd × 45 in; at 60 in wide the same area needs 2.5 × 45 ÷ 60 = 1.875 yd.
- 1.875 ÷ 2.5 − 1 = −25%, so you need a quarter less fabric.
2.5 yards of 45-inch fabric converts to 1.875 yards (about 1⅞ yd) of 60-inch fabric.
What the result means
Round up to the next cut your shop sells, and add extra for one-way designs, nap, pile or pattern matching, which an equal-area conversion cannot see.
Assumptions and limits
- Both widths are usable widths, excluding selvedges.
- Pattern pieces can be laid out as efficiently on either width.
- Large pieces that do not fit across a narrow fabric need more length than the area rule suggests.
Questions
Is this the same as a fabric conversion chart?
Yes. Printed charts are equal-area conversions rounded up to convenient fractions of a yard.
Should I add extra?
Add 10–15% for directional prints, velvet or plaid matching, and for pre-wash shrinkage.