48AA Bra Size
Everything you need to know about bra size 48AA — measurements, sister sizes, international equivalents, and fit advice.
Last reviewed on 28 April 2026.
Measurements for 48AA
48AA is built for an underbust ribcage measurement that falls in the 47–49 inch range, with a full-bust measurement around 49 inches. The band number — 48 — is a fuller band size where most of the support comes from a strong, snug band rather than the straps. The cup letter — AA — describes the difference between the two measurements; an AA cup means the full bust is roughly the same as the underbust — there is little projection, and the cup mostly serves as smooth coverage rather than tissue support.
48AA in Other Sizing Systems
EU, FR, and JP sizing read the band in centimetres, which is why 48AA maps to 110AA (EU), 125AA (FR), and 110AA (JP) — the same body, expressed in different units. AU sizing uses a small numeric scale (26AA for this band). UK sizing shares the band number with the US but parts ways at the cup once you go past D, so 48AA reads as 48AA on a UK label.
Sister Sizes for 48AA
These sizes have the same cup volume as 48AA. 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 48AA 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 48AA
AA cups can be hard to find in mainstream stores. Brands and ranges focused on petite or smaller-cup fitting tend to carry more options, often in soft-cup, bralette, or triangle styles.
If your 48AA 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 48AA 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 48AA is right for you.
48AA — frequently asked questions
What measurements are a 48AA bra?
A 48AA bra fits an underbust (ribcage) measurement of roughly 47 to 49 inches (119–124 cm) and a full-bust measurement of about 49 inches (124 cm). The cup letter AA reflects the difference between those two numbers.
What are the sister sizes of 48AA?
The sister sizes of 48AA are 46A. They share the same cup volume as 48AA but use a different band — go to 46A for a tighter band, or up for a looser one. Try a sister size when the cup of your 48AA fits but the band feels too loose or too tight.
What is 48AA in UK, EU, and other sizing systems?
48AA (US) converts to 48AA in UK sizing, 110AA in EU sizing, 125AA in French sizing, 26AA in Australian sizing, and 110AA in Japanese sizing. The body is the same; only the labelling system changes.
Is 48AA a small or large bra size?
In terms of how common it is, this size pairs a fuller band with a smaller 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 compact end.
Not sure about your size? Measure yourself and double-check.
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