International Bra Size Conversion Guide: US, UK, EU, FR, JP, and AU

7 min read•June 9, 2026•Reviewed: June 9, 2026

✓Reviewed by Apex Conversion Editorial Team · Last reviewed June 9, 2026

Bra sizing uses two components — a band size around the ribcage and a cup size for bust volume — and nearly every region encodes them differently. The US and UK use band numbers in inches (32, 34, 36), continental Europe uses centimeters rounded to the nearest 5 (70, 75, 80), France and Spain add 15 to the EU number (85, 90, 95), and Japan uses the EU-style centimeter band but lists the cup first (B75 rather than 75B).

Cup sizes diverge even more than bands. The letters A through D are roughly aligned across systems, but beyond D each region follows its own progression — a US DDD is a UK E, and a Japanese D cup is closer to a US C. This guide maps all six major systems and explains the conversions that size charts often oversimplify.

Band Size Systems by Region

US and UK bands are even numbers derived from the underbust measurement in inches: a snug 30-inch underbust typically corresponds to a 30 or 32 band depending on the brand's fitting method. EU bands are the underbust measurement in centimeters rounded to the nearest 5: a 76 cm underbust wears a 75 band. The two systems align approximately as US 30 = EU 65, US 32 = EU 70, US 34 = EU 75, US 36 = EU 80, continuing in steps of one US size to 5 EU centimeters.

France, Belgium, and Spain use the EU centimeter system plus 15: an EU 75 is a French 90. Italy uses small integers (1, 2, 3...) where size 1 ≈ EU 65. Australia and New Zealand use dress-size-style numbers: an AU 12 band corresponds to a US 34. Japan, South Korea, and China use EU-style centimeter bands, so the band number itself converts directly — only the cup needs adjustment.

Cup Size Progressions and Sister Sizes

A cup letter encodes the difference between the bust and band measurements — roughly one inch (2.5 cm) per letter. A–D are broadly comparable everywhere, but the systems split afterward: the US typically runs D, DD, DDD, G; the UK runs D, DD, E, F, FF, G; continental Europe runs D, E, F, G with no doubled letters. Japanese cups run about one letter smaller in volume than US cups — a JP C is close to a US B.

Sister sizes are equivalent cup volumes on different bands: going down one band while going up one cup (34C → 32D) keeps the same cup volume with a tighter band. Sister sizing matters for conversion because international size charts sometimes shift both numbers — if a converted size feels wrong in the band, the correct fix is usually the sister size, not a different cup.

Quick Band Conversion Reference

US/UK → EU:   30→65, 32→70, 34→75, 36→80, 38→85, 40→90
EU → FR/ES:   FR = EU + 15  (75 → 90)
EU → IT:      65→1, 70→2, 75→3, 80→4, 85→5
US → AU:      30→8, 32→10, 34→12, 36→14, 38→16
EU → JP:      same number, cup listed first (75B ↔ B75)

Cup alignment (approximate):
  US:  A  B  C  D  DD  DDD  G
  UK:  A  B  C  D  DD  E    F
  EU:  A  B  C  D  E   F    G
  JP cups run ~1 size smaller than US

Conversion charts are starting points, not guarantees. Band elasticity, cup shape, and sizing philosophy vary significantly between brands — European brands often run firmer in the band than US brands at the same converted size. When ordering internationally, check the brand's own size chart and measure rather than relying on your usual size.

Frequently Asked Questions

What is a US 34C in European sizing?

A US 34C converts to approximately EU 75C. The band converts as 34 → 75; the C cup is broadly aligned between the two systems at this size.

Are US and UK bra sizes the same?

Bands are the same (both inch-based), and cups match through D. Beyond D they diverge: US DD = UK DD, but US DDD = UK E, and the systems continue to differ from there.

What is a French bra size 90 in US sizing?

French 90 = EU 75 = US/UK 34. France and Spain add 15 to the European centimeter band number.

Why does my converted size not fit?

Cup progressions, band tension, and fit philosophy differ by brand and region. If the cup fits but the band doesn't, try the sister size (band down, cup up — or the reverse). Japanese-market bras in particular run smaller in cup volume than the same letter in US sizing.

Try the Bra Size Converter

👙 Open Bra Size Converter →