Free converter · sewing units
Type an inch fraction like 5/8 or 1⅜ and get millimeters and centimeters. Go the other way to the nearest 1/8, 1/16 or 1/32 inch, and convert fabric amounts between yards and meters.
1 in = 25.4 mm exactly; 1 yd = 0.9144 m exactly. Fractions are rounded to the nearest step.
How it works
Find the measurement in the pattern or book, such as a 5/8 in seam allowance.
Type it as written: 5/8, ⅝, 1-3/8 or 1.5 cm. Common values are one tap away.
Use the converted value on your seam gauge, ruler or machine plate.
Worked example
Worked example
Result
At 1/16 resolution, 1 cm is closest to 3/8" (0.5 mm shorter). Round fabric amounts up, never down.
Reference
| in | Decimal | mm | cm |
|---|---|---|---|
| 1/16" | 0.0625 | 1.59 | 0.16 |
| 1/8" | 0.125 | 3.18 | 0.32 |
| 3/16" | 0.1875 | 4.76 | 0.48 |
| 1/4" | 0.25 | 6.35 | 0.64 |
| 5/16" | 0.3125 | 7.94 | 0.79 |
| 3/8" | 0.375 | 9.53 | 0.95 |
| 7/16" | 0.4375 | 11.11 | 1.11 |
| 1/2" | 0.5 | 12.7 | 1.27 |
| 9/16" | 0.5625 | 14.29 | 1.43 |
| 5/8" | 0.625 | 15.88 | 1.59 |
| 11/16" | 0.6875 | 17.46 | 1.75 |
| 3/4" | 0.75 | 19.05 | 1.91 |
| 13/16" | 0.8125 | 20.64 | 2.06 |
| 7/8" | 0.875 | 22.23 | 2.22 |
| 15/16" | 0.9375 | 23.81 | 2.38 |
| 1" | 1 | 25.4 | 2.54 |
| cm | Nearest 1/8" | Nearest 1/16" |
|---|---|---|
| 0.5 | 1/4" (+1.35 mm) | 3/16" (−0.24 mm) |
| 0.6 | 1/4" (+0.35 mm) | 1/4" (+0.35 mm) |
| 0.7 | 1/4" (−0.65 mm) | 1/4" (−0.65 mm) |
| 1 | 3/8" (−0.48 mm) | 3/8" (−0.48 mm) |
| 1.2 | 1/2" (+0.7 mm) | 1/2" (+0.7 mm) |
| 1.5 | 5/8" (+0.88 mm) | 9/16" (−0.71 mm) |
| 2 | 3/4" (−0.95 mm) | 13/16" (+0.64 mm) |
| 2.5 | 1" (+0.4 mm) | 1" (+0.4 mm) |
| 3 | 1 1/8" (−1.43 mm) | 1 3/16" (+0.16 mm) |
| 4 | 1 5/8" (+1.28 mm) | 1 9/16" (−0.31 mm) |
| 5 | 2" (+0.8 mm) | 1 15/16" (−0.79 mm) |
| yd | m | Buy |
|---|---|---|
| 1/8 | 0.114 | 0.2 m |
| 1/4 | 0.229 | 0.3 m |
| 1/2 | 0.457 | 0.5 m |
| 3/4 | 0.686 | 0.7 m |
| 1 | 0.914 | 1.0 m |
| 1 1/2 | 1.372 | 1.4 m |
| 2 | 1.829 | 1.9 m |
| 3 | 2.743 | 2.8 m |
The figures in brackets show how far each fraction is from the exact value. Fabric amounts are rounded up to the next 0.1 m.
The math
Both factors are exact by definition. To go back to inches, divide by 25.4 and round to the nearest 1/8, 1/16 or 1/32. The converter shows how far the rounded fraction is from the exact value.
5/8 = 0.625 in; 0.625 × 25.4 = 15.9 mm. 1.5 cm ÷ 2.54 = 0.591"; the nearest 1/8 is 5/8", 0.9 mm longer than exact.
Tips
Convert once at the start and sew in that system. Mixing rounded values adds up across a garment.
They differ by under 1 mm per seam. That is fine for one seam but adds up over many panels.
Always round yardage up to the next 1/8 yd or 0.1 m. Shops cut in those steps.
The fabric yardage calculator works in either system and handles fabric width too.
5/8 in = 1.5875 cm, about 15.9 mm. Most metric patterns use 1.5 cm for the same seam.
1.5 cm = 0.591". The nearest 1/8 inch is 5/8"; on a 1/16 scale it is 9/16".
Yes. Unicode fractions, mixed numbers with a space or a hyphen, decimals, and feet and inches like 2' 3" all work.
Exactly 0.9144 m. 1 3/8 yd is 1.26 m, so buy 1.3 m.
Seam gauges and quilting rulers are marked in 1/8 and 1/16. Use 1/32 only for precise drafting.
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