Sizing Guide — The History of the Brassiere

Before you convert

How to measure for a bra

Every sizing system starts from the same two numbers. Use a soft measuring tape, wear a thin unlined bra or none at all, and stand naturally — don't hold your breath or pull the tape tight.

A measuring tape wrapped around a dress form at the ribcage, showing where to measure the band

1Band
Wrap the tape around your ribcage directly under your bust, right where a bra band would sit. Keep it level and snug against the body without digging in. If the number lands on an odd inch, round up to the nearest even number.
2Bust
Wrap the tape around your back and across the fullest part of your chest, over the apex. The tape should sit comfortably — not compressed, not loose.

Do the math

Find your cup size

Subtract your band measurement from your bust measurement. Each inch of difference corresponds to roughly one cup size, using the US letter sequence as the baseline.

Bust minus band → cup size (US)
Difference	0"	1"	2"	3"	4"	5"	6"	7"	8"
Cup	AA	A	B	C	D	DD / E	DDD / F	G	H

Worked example

A 34" bust and a 29" underbust is a 5" difference — that rounds to a 30 band (nearest even number) with a DD/E cup, so a 30DD or 30E depending on the brand's labeling.

Sizing around the world

Same measurements, different labels

Every system pairs a band number with a cup letter, but no two countries label them the same way. Bands run in inches in the US and UK, centimeters in the EU and Japan, an offset centimeter scale in France, and small whole numbers in Italy. Cup letters line up neatly through D — then every system splits off in its own direction.

Band size by country (common range)
US / UK (in)	EU / Japan (cm)	France / Spain (cm)	Italy	Australia / NZ
32	70	85	2	10
34	75	90	3	12
36	80	95	4	14
38	85	100	5	16
40	90	105	6	18

Real-world equivalent sizes
US	UK	EU	France	AU / NZ	Japan	Italy
32C	32C	70C	85C	10C	70C	2C
34D	34D	75D	90D	12D	75D	3D
36DD / E	36DD	80E	95E	14DD	80E	4E
32G	32F	70G	85G	10F	70G	2G

Below a D cup, the letters mostly agree — a US C and a UK C describe roughly the same volume. Above that, the UK inserts extra double letters (DD, FF, GG) that the US and most of Europe skip, so UK labels start to run "behind" the others. That last row is the clearest example: a UK 32F sits at roughly the same volume as a US 32G and a European 70G.

Use this as a starting point, not a guarantee

Conversion charts translate the label, not the fit. Wire width, cup depth, fabric stretch, and how a specific brand grades its pattern all shift the result. When ordering from a new country or brand, check that retailer's own size chart before converting by table alone.

Getting the fit right

What a bad fit actually looks like

Label aside, these are the visual tells that a band or cup is off in either direction.

Cup or band too small

Spilling, digging, and a lifted gore

A bra on a dress form fitting too small, with strained cups and a tight band

1Breast tissue bulges over the top or sides of the cup — the classic "quad boob" look, a sign the cup itself is too small.
2The center gore doesn't sit flat against the sternum; it lifts or floats away because the cups don't have room to close.
3Straps dig into the shoulders and leave marks, often because an overly tight band and cup are pushing more of the load onto them.

Cup or band too big

Gaping, slipping, and a rising band

A bra on a dress form fitting too big, with gaping cups and a slipping strap

1The cup fabric wrinkles or gapes, with visible empty space at the top — structured cups gap, unlined ones fold and pucker.
2Straps slide off the shoulder repeatedly because the band isn't snug enough to anchor them.
3The band rides up in back, curving toward the shoulder blades instead of sitting level, because it's too loose to carry the weight on its own.