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30A Bra Size - UK, EU and Sister Size Conversions
Everything about the 30A bra size: international conversions, sister sizes, and how to check your fit.
Underbust
29-31 in / 74-79 cm
Bust
30.5-31.5 in / 77-80 cm
These are the body measurements that typically map to 30A. Measure to confirm because brands vary.
Last updated: July 9, 2026
US bra size
30A
- UK
- 30A
- EU
- 65A
- FR
- 80A
- AU
- 8A
Snugger band
Outside the active MVP range.
Looser band
Outside the active MVP range.
Is 30A big or small?
30A combines a 30 band, which is on the smaller end of this MVP band range, with A, which is a lower cup step. Cup letters are relative to band size, so fit can still vary by brand and style.
People often search "is 30A big" or "is 30A small", but the answer depends on both the 30 band and A cup step. Use the size label as a starting point, then confirm it with a real fit check.
What does 30A mean?
In 30A, the 30 is the band size: it describes the measurement around your ribcage under the bust. The A is the cup step, and cup volume changes with the band, so A on a 30 band is not the same volume as A on every other band.
For this dataset, 30A sits at a smaller cup step in this size range. Use that as context, not as a judgment about your body or shape.
How to tell if your 30A fits
- The band should stay level across your back when you move.
- Cups should hold breast tissue without spilling, gapping, or wrinkling.
- The center gore should sit close to your body if the style has wires.
- Straps should help shape the fit, not carry most of the support.
30A sister sizes explained
Sister sizes adjust the band and cup in opposite directions, which can keep the cup volume close while changing how firm the band feels.
Use the sister size finder when the cup feels close but the band needs a better fit, or read sister sizes explained for when the idea helps and where it stops.
Bra styles by breast shape
The same 30A can look and fit differently depending on breast shape. Round, teardrop, east-west, and other shapes suit different bra styles.
Common fit problems in 30A
Band rides up
If a 30A band rides up, use the sister-size finder to look for a snugger band.
Cup gaps
If the cup has empty space, first check shape and measuring accuracy before changing the band.
Cup spills
If tissue spills over the edge, compare 30B or a fuller-cup style.
Band feels too tight
If the band feels too firm, use the calculator again and compare nearby supported sizes.
Convert 30A to another system
Bra size charts for 30A
Use the chart pages when you want to compare 30A against full country size tables instead of opening one conversion at a time.
Popular 30A searches
Related sizes
Bra styles that work well for 30A
- For 30A, a firmer adjustable band can help small-band sizes feel secure.
- Because A is relative to the 30 band, shallow or lightly lined cups may reduce extra space.
- If the cup edge gaps or cuts in, compare the shape as well as the size label.
- If the band feels right but cup space is off, compare 30B as a nearby cup step.
FAQ
Is 30A a big or small bra size?
30A depends on both the 30 band and the A cup step. Cup letters are relative to band size, so it is more useful to focus on fit than on whether a size sounds large or small.
What does 30A convert to in UK sizing?
In this sizing table, 30A converts to UK 30A. Brand charts can still differ, so check the retailer's chart before buying.
What sister size should I try from 30A?
If the band feels tight, try the next looser band with a smaller cup step. If the band rides up, try the next snugger band with a larger cup step.
What measurements usually make 30A?
30A usually maps to an underbust around 29-31 in / 74-79 cm and a bust around 30.5-31.5 in / 77-80 cm. Use these as calculator-aligned starting measurements, then confirm the fit because brands vary.
Why is my UK bra size different from my US size?
US and UK cup labels do not always move in the same sequence, especially after D. A conversion is a guide, not a replacement for trying the bra on.
How accurate is an online bra size calculator?
It can give you a sensible starting point from your measurements. Shape, style, fabric, and brand sizing still decide whether the bra actually fits.
Bras in your size
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