Bra Size Calculator

Measure without a padded bra, or wearing a thin unlined one, with a soft tape held level all the way around. For the band, wrap the tape snugly around the ribcage directly under the bust and breathe out; for the bust, measure loosely around the fullest part while standing straight. The calculator rounds the underbust to the nearest even band size and counts one cup size for every inch of difference between the bust and that band.

Incorrect bra fit

Surveys by retailers and studies of fitting clinics have repeatedly found that a large share of people wear the wrong bra size, most often a band that is too big and a cup that is too small. The band provides most of a bra's support, so a loose band shifts the load onto the straps and shoulders.

Signs of a poor fit include a band that rides up at the back, straps that dig in or keep slipping, cups that gap or wrinkle, breast tissue spilling over the top or sides of the cups, and an underwire that sits on breast tissue instead of the ribcage or lifts away from the chest at the center. A well-fitting band sits level and feels firm on the loosest hook when new, so it can be tightened as the elastic stretches.

Size also changes over time with weight changes, pregnancy and breastfeeding, hormones and age, so it is worth measuring again every year or two, and whenever bras start to feel uncomfortable.

Bra size

A bra size has two parts: a band size for the ribcage measurement and a cup letter for the volume of the bust relative to the band. Cup letters are relative, not absolute. A 32D and a 38D have different cup volumes; the 32D's cup is the same volume as a 34C or a 36B, which are called sister sizes.

The United States, Canada and the UK measure bands in inches; Europe uses centimeters in steps of 5 under the EN 13402 standard, France, Belgium and Spain add 15 to the European band, and Australia and New Zealand use dress-size numbers. Cup letters agree up to D but then diverge: after D the UK uses DD, E, F, FF, while US brands often use DD, DDD, G and European brands E, F, G.

Older US fitting advice added 4 or 5 inches to the underbust to get the band, which tends to produce bands that are too large and cups that are too small; many fitters now use the underbust measurement itself. The calculator shows both. The tables show how band and cup sizes line up across systems.

Cup letters by bust-minus-band difference in each system:

Frequently asked questions