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Body measurements for sewing patterns
Convert cun, inches, and centimeters when measuring a body for patterns.
A pattern only fits if the tape, the draft, and the finished garment speak the same unit.
Commercial envelopes, indie PDFs, and custom tailoring still mix three length systems: centimeters on metric blocks, inches on US/UK blocks, and Chinese cun (市寸) on many East Asian drafting methods. This guide shows how to take a body measurement once and convert it without mixing the Chinese cun with the Japanese sun.
What to measure
Start with the measurements the pattern actually asks for. A typical dress or shirt block needs bust or chest, waist, hip, back length, and sleeve length. Record each value with the unit printed on the tape. If the tape shows both cm and inches, pick one column and stay with it until you convert on purpose.
Exact factors
Use these registry values:
1 inch = 2.54 cm exactly
1 cm = 0.3937007874 in
1 Chinese cun (市寸) = 1/30 m = 3.333... cm ≈ 1.312 in
1 Chinese chi (市尺) = 10 cun = 1/3 m ≈ 13.123 in
Japanese 寸 (sun) is a different unit: 1 sun = 1/33 m ≈ 3.030 cm. Do not treat sun as cun when you are comparing a Chinese drafting book with a Japanese wasai text.
Worked example
A bust of 92 cm is 92 / 2.54 ≈ 36.22 in. The same bust in Chinese cun is 92 / (100/30) = 27.6 cun. If a vintage Chinese pattern lists a 2.6 chi waist, convert chi to inches first (2.6 × 13.123 ≈ 34.12 in), then to cm (34.12 × 2.54 ≈ 86.7 cm).
Conversion table
| Body measure | cm | inch | cun |
|---|---|---|---|
| Bust | 84 | 33.07 | 25.2 |
| Bust | 88 | 34.65 | 26.4 |
| Bust | 92 | 36.22 | 27.6 |
| Bust | 96 | 37.80 | 28.8 |
| Waist | 68 | 26.77 | 20.4 |
| Waist | 76 | 29.92 | 22.8 |
| Hip | 92 | 36.22 | 27.6 |
| Hip | 100 | 39.37 | 30.0 |
Tools
Measure twice, convert once, and write the unit next to every number on the pattern sheet.