34G Bra Is Equivalent to What Other Size? | Sister Sizes Chart

Finding the right bra size can feel like decoding a secret language, and a 34G is one of the most commonly misunderstood. The number refers to your band measurement (34 inches), while the letter represents your cup volume. The challenge is that “G” doesn’t mean the same thing everywhere. Most brands build their sizing on either the UK system or the US system, and the difference between them shifts how the cups scale. That’s why a 34G from one brand might feel like a different size from another, and why understanding your sister sizes is the real key to a good fit.

What Are Sister Sizes For A 34G Bra?

Sister sizes are the quickest way to get a comparable fit. They change your band size by one step while adjusting the cup letter to keep the same volume. For a 34G, this helps you find a better fit if the band feels too tight or too loose.

Whichever system you’re in, the goal is the same: keeping the cup volume identical while letting the band do the work.

Does 34G Change Between UK And US Sizing?

Yes, and this is where most of the confusion happens. The “G” cup is not a universal label.

That range matters because the letters are not consistent across regions. For example, the UK’s GG cup is a full size larger than a plain G, while US brands often don’t use the double-letter format at all. This is why you can’t simply order the same letter internationally and expect the same fit.

Why Does Fit Vary Between 34G Brands?

Fit varies because patterns, fabrics, and band-stretch differ. A bra labeled 34G from a UK brand like Bravissimo is built to UK specifications, which rely on the double-letter scale. A US brand using the same 34G label expects its own cup shape to work. Both are “correct” within their own systems, but your body doesn’t care about the label. The band should feel firm on the loosest hook, and the cups should encase your tissue fully without any spillover or gap.

You might also fit a 34GG or a 34F depending on the cut and the style. A plunge bra could fit tighter, while a full-coverage cup runs roomier. The most reliable route is to try on a few sister sizes in the specific brand you want to buy. That’s still less work than returning a bra that looked perfect online. If you are ready to shop, our tested roundup of the best 34G bras on the market details which styles and brands run true to size.

How To Convert 34G For International Shopping

International conversion charts are helpful shortcuts, but they never beat wearing the bra. The chart below compresses the most common conversions for a 34G into a single row. Use it to start your search, then verify the band’s stretch and cup shape once the bra arrives.

When you buy from a site like ASOS, which carries both UK and US labels, check which sizing system the product page lists before you add it to your cart. A single wrong letter can shift the fit by an entire cup volume.

The bottom line is to treat any conversion as a starting point rather than the last word. Measure your underbust and your fullest bust with a soft tape, compare those numbers to the brand’s own chart, and buy the size that matches that chart. If the brand’s chart is unclear, order a sister size or two to compare.