34G Bra Size
34G fits a 33–35 inch (84–89 cm) underbust and a full bust of about 42 inches (107 cm). Its sister sizes are 32H and 36DDD.
Last reviewed on 25 September 2026.
34G at a glance
| Underbust (band) | 33–35 in · 84–89 cm |
|---|---|
| Full bust | ≈ 42 in · 107 cm |
| Bust minus underbust | ≈ 8 in · 20 cm |
| Sister sizes (same cup volume) | 32H · 36DDD |
| UK / EU / FR / AU | 34F · 75G · 90G · 12F |
| One cup bigger | 34H |
| One cup smaller | 34DDD |
| Approx. top size | M · UK 10–12 / US 6–8 |
Measurements for 34G
34G is built for an underbust ribcage measurement that falls in the 33–35 inch range, with a full-bust measurement around 42 inches. The band number — 34 — is one of the most widely produced band sizes, with broad style choice. The cup letter — G — describes the difference between the two measurements; a G cup (US) means the full bust is about eight inches larger than the underbust — the same volume is an F in UK sizing. At this volume, three-part cups and side support panels usually fit more cleanly than thin moulded cups.
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34G in Other Sizing Systems
EU, FR, and JP sizing read the band in centimetres, which is why 34G maps to 75G (EU), 90G (FR), and 75G (JP) — the same body, expressed in different units. AU sizing uses a small numeric scale (12F for this band). UK sizing shares the band number with the US but parts ways at the cup once you go past D, so 34G reads as 34F on a UK label.
Sister Sizes for 34G
These sizes have the same cup volume as 34G. Try them if the band feels too tight or too loose.
← Tighter band, bigger cup · Looser band, smaller cup →
Sister sizes are useful when the cup of your 34G fits well but the band is wrong — too loose by the end of the day, or too tight to clip up comfortably. Going one band smaller and one cup larger keeps the cup volume the same while tightening the band; going the other way loosens the band without losing cup space. Read the full sister-size matrix if you want to see how this works for every size at once.
Fit Tips for 34G
G cups generally need well-engineered bras with strong band tension and reinforced wires. Look for ranges that specialise in fuller-bust fitting rather than mainstream sizes that stop at DD.
If your 34G bra is gapping at the top of the cup, the cup may be too large or the wrong shape — try a demi-cup or balconette before assuming the size is wrong. If the centre piece between the cups (the gore) does not lay flat against your sternum, the cup is almost certainly too small; go up one cup. If the band rides up across your back during the day, the band has stretched out or was too loose to begin with — drop one band size and add one cup to keep the same cup volume.
For more detailed troubleshooting, the Fit Test on the home page covers six common visible problems and the size or shape change that usually addresses each one. The guide to measuring mistakes covers the most common reasons a calculation comes out wrong in the first place.
Related sizes
If 34G is close but not quite right, these neighbouring sizes are the most useful next places to look:
See every size at a glance on the full bra size index, or read how to measure your bra size if you are not sure 34G is right for you.
34G — frequently asked questions
What measurements are a 34G bra in inches and cm?
A 34G bra fits an underbust (ribcage) measurement of roughly 33 to 35 inches (84–89 cm) and a full-bust measurement of about 42 inches (107 cm). The cup letter G reflects the roughly 8-inch (20 cm) difference between those two numbers.
What size is equivalent to 34G? (sister sizes)
The sister sizes of 34G are 32H (tighter band, one cup letter up) and 36DDD (looser band, one cup letter down). They hold the same cup volume as 34G on a different band. Try a sister size when the cups of your 34G fit but the band feels too loose or too tight.
What is 34G in UK, EU, and other sizing systems?
34G (US) converts to 34F in UK sizing, 75G in EU sizing, 90G in French sizing, 12F in Australian sizing, and 75G in Japanese sizing. The body is the same; only the labelling system changes.
Is 34G a small or large bra size?
In terms of how common it is, this size pairs an average band with a fuller-bust cup. There is no universal "small" or "large" bra size — the same cup letter describes a different volume on every band — but within the full range BraCalc covers (bands 28–48, cups AA–H) this combination sits toward the fuller end.
Is 34G a small, medium, large, or XL?
As a rough guide, a 34 band usually matches size M in tops and bralettes — around UK dress size 10–12 (US 6–8). The band number drives this more than the cup letter, so 34G lands in the same letter size as other 34-band bras. With a fuller cup, many people go one size up in fitted tops so the bust has room. Letter sizing varies a lot between brands, so always check the brand's own chart.
What is the next size up or down from 34G?
Keeping the same 34 band, one size up in the cup is 34H, and one size down is 34DDD. If you want a bigger or smaller band but the same cup volume, use a sister size instead: 32H or 36DDD. Remember that the cup letter is relative to the band — 36G has more cup volume than 34G, not the same.
Not sure about your size? Measure yourself and double-check.
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