Chapter 77: Measurement Conversion Charts

This chapter provides standard unit conversion references for the body and garment measurements discussed throughout Parts VII, VIII, and IX.

Length Conversions (Inches to Centimeters)

Inches	Centimeters
1 in	2.54 cm
5 in	12.7 cm
10 in	25.4 cm
20 in	50.8 cm
24 in	61.0 cm
28 in	71.1 cm
30 in	76.2 cm
32 in	81.3 cm
34 in	86.4 cm
36 in	91.4 cm
40 in	101.6 cm

Approximate Waist Circumference: US Size to Inches/Centimeters

US Size (approx.)	Waist (in)	Waist (cm)
0	24–25	61–63.5
2	25–26	63.5–66
4	26–27	66–68.5
6	27–28	68.5–71
8	28–29.5	71–75
10	29.5–31	75–79
12	31–33	79–84
14	33–35	84–89
16	35–37	89–94

As emphasized in Chapter 72, these figures are approximate and illustrative only — actual brand-specific size charts vary considerably and should always be consulted directly rather than relying on general size-to-measurement tables such as this one.

Fabric Weight Conversions

GSM (g/m²)	Oz/yd² (approx.)
100 GSM	~2.95 oz/yd²
150 GSM	~4.4 oz/yd²
200 GSM	~5.9 oz/yd²
250 GSM	~7.4 oz/yd²
300 GSM	~8.85 oz/yd²
350 GSM	~10.3 oz/yd²

Common Seam Allowance Conversions

Metric	Imperial (approx.)
1 cm	~ 3/8 in
1.5 cm	~ 5/8 in
2 cm	~ 3/4 in
2.5 cm	~ 1 in

Practical Note: When converting pattern measurements between metric and imperial systems, it is best practice to complete all pattern drafting (Chapter 37) in a single unit system throughout, converting only at the very start or end of a project, rather than mixing units mid-draft, which is a common and easily avoidable source of drafting error.