US to UK conversion

34B in UK Bra Size

Convert 34B from US sizing to UK sizing, with the full international table, nearby sister sizes, and fit checks in one place.

Instant answer

34B (US) =

34B UK

In this sizing table, 34B in US sizing converts to 34B in UK sizing.

Sizing varies by brand

A conversion gives you the closest label in another sizing system, but brands can grade cups, wires, and bands differently. Use the converted size as a starting point, then check the retailer's chart and the fit of the actual bra.

Before you buy in UK sizing

Use 34B as the translated label, not as a fit guarantee.
Check the retailer's size chart because some brands grade bands and cups differently.
If the cup volume feels close but the band changes, compare sister sizes before switching cup letters.
When possible, check return rules before buying across sizing systems.

Full conversion table for 34B

34B bra size conversion across US, UK, EU, French, and Australian sizing.
US	UK	EU	FR	AU
34B	34B	75B	90B	12B

Bra sizing varies between brands. Use this as an accurate starting point and check the fit.

Sizes near 34B in UK sizing

If 34B is close but not right, these are the neighbouring US sizes and what each one becomes in UK sizing. Band neighbours change the fit around the ribcage; cup neighbours change volume.

US sizes adjacent to 34B and their UK equivalents.
US size	UK size	How it differs
32B	32B	One band step snugger, same cup letter.
36B	36B	One band step looser, same cup letter.
34A	34A	One cup step down, same band.
34C	34C	One cup step up, same band.

What this conversion means

For 34B, the band stays tied to the 34 US band while the label is translated into UK sizing. In this dataset, 34B (US) converts to 34B (UK). Treat that as the starting label, then check the brand chart and the real fit.

Sister sizes for 34B

Sister sizes: 32C and 36A can be worth checking when the cup volume feels close but the band needs a different feel.

What measurements make a 34B?

34B is built from a band measurement and a bust measurement, not from the label alone. In the current calculator formula, the closest starting range is about 33-35 inches (84-89 cm) under the bust and about 35.5-36.5 inches (90-93 cm) around the fullest part of the bust. The band comes from the underbust rounding, while the cup step comes from the difference between bust and band.

Is 34B big or small?

34B is not automatically big or small; it depends on the band and the cup together. In this size set, the US equivalent uses a middle band and a lower cup step. Cup letters are relative to the band, so a D on one band is not the same volume as a D on every other band. The most useful question is whether the band stays level and the cups hold smoothly, not whether the label sounds large or small.

If 34B doesn't fit right

Band rides up: The band may be too loose or stretched out; try a snugger band or compare the snugger sister size.

Cups gape: The cup may be too roomy, too deep, or pulled away by a loose band; check the band before changing cup volume.

Cups spill: The cup volume may be too small or the cup shape may be too closed; try one cup step up before changing the band.

Straps dig in: The straps may be compensating for a band that is not supporting enough; reset the band fit before tightening straps.

How 34B differs between brands

Two brands can print 34B or its equivalent on the tag and still cut the bra differently. A firmer elastic can make the same band feel smaller, and a shallow or narrow cup can make the same cup letter feel different. Check the retailer chart, read fit notes when available, and compare the label against the brand and region sizing guide before treating the conversion as final.

Shopping for 34B

When shopping for 34B, start with styles that make the band easy to judge. If the cup is in a lower or middle step, lightly lined T-shirt styles can make gaps easy to spot. Fuller cup steps often benefit from styles with steadier side support, deeper cups, or a balconette shape depending on breast shape. For special outfits, compare the fit needs in the outfit guides before choosing a strapless, plunge, or backless option.

Bras in your size

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Everyday Fit Store

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Comfort Band Co.

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Soft Cup Edit

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FAQ

Is 34B in the US the same as UK sizing?

The closest UK label here is 34B. It is a conversion guide, so retailer charts and try-on fit still matter.

What is 34B in Australian sizing?

In this same table, 34B converts to 12B (AU). That helps when a retailer shows a Australian chart instead of a UK one.

How do I know if 34B fits?

Start with the band: it should feel firm and even around your ribcage. Then check cup containment and comfort across the style you are actually trying on.

What sister sizes work with 34B?

32C and 36A are the closest sister-size options for 34B in this dataset. Try a sister size when cup volume feels close but the band needs to feel snugger or looser.

Why do bra sizes differ between countries?

Countries and brands do not all use the same band labels or cup-letter sequence. A conversion translates the closest standard label, but the final fit still depends on the specific bra.

What measurements usually make 34B?

The current calculator formula points to about 33-35 inches underbust and 35.5-36.5 inches bust, or roughly 84-89 cm and 90-93 cm. Treat that as a starting range and then check the real fit.