Dress Size Calculator

Ready to wear dress sizing is a nearest neighbour matching problem rather than a formula. A published chart lists a bust, waist and hip value for each size code, and this tool scores every row by the sum of absolute differences from your three measurements, then reports the row with the smallest total. Because that sum weights all three dimensions equally, a body whose bust and hips sit two sizes apart matches a compromise row that fits neither perfectly, which is why the separate bust, waist and hip sizes are also shown. Typical US chart steps are about 1 inch of bust per size at the small end, with US 0 at roughly 31 inches, widening to 1.5 to 2 inches per size above US 12. The body shape labels come from differences rather than absolute values. A bust minus waist and a hip minus waist of about 7 inches or more each is conventionally called an hourglass; a hip minus waist of 9 inches or more with a smaller bust drop is a pear; under about 4 inches of difference in both directions is a rectangle. The main caveat is that no law governs what a size label means in the United States, so a chart match is a starting point, not an answer. Garment ease, meaning the extra measurement built into a pattern beyond body size, differs by several inches between a woven sheath and a jersey wrap dress, and knits containing elastane tolerate a full size of error where a structured woven does not.

Systematic women's sizing in the United States begins with a Depression era measuring campaign. Between 1939 and 1940 Ruth O'Brien and William Shelton conducted a survey for the US Department of Agriculture, measuring roughly 15,000 women, and published the results in 1941 as Miscellaneous Publication 454, Women's Measurements for Garment and Pattern Construction. Because participants were paid, the volunteer sample skewed young, white and low income, which limited how representative the resulting proportions were. The data nonetheless became the basis for Commercial Standard CS 215-58, issued by the National Bureau of Standards in 1958, which fixed the even numbered size run and tied each number to a bust measurement. That standard was revised in 1970 and withdrawn entirely in 1983, leaving American sizing voluntary. ASTM International later published body measurement tables, including D5585 for adult women, first issued in 1994 and revised since, but manufacturers are free to ignore them. Without enforcement, labels drifted downward through the practice known as vanity sizing, so a set of measurements that once carried one number now carries a smaller one. The SizeUSA project of 2002 to 2003, which used three dimensional body scanners on roughly 10,000 volunteers, documented how far the measured population had moved from the 1941 proportions. Internationally, ISO 8559 and the European EN 13402 series took the opposite route, designating sizes by the body measurements themselves in centimeters.