28G Bra Size Guide: Measurements, Fit, Sister Sizes & Conversions

Last updated: August 2026

The 28G bra size pairs a 28 band with a G cup. This guide breaks down exactly what that means in real measurements, how to tell whether 28G is truly your size, which sister sizes to reach for, and how 28G converts around the world.

Band 28G cupUnderbust 27–28″Bust 35–36″

What a 28G bra actually means

Read a bra size as two parts. The 28 is the band, and it comes straight from your underbust — the snug measurement around your ribcage just beneath the bust. The G is the cup, and it comes from how much bigger your bust is than that underbust: about 7–8 inches more for a G cup. The cup letter is a difference, not a fixed volume — which is why the very same cup looks different on a narrow band than on a wide one.

28G measurements

If your own numbers land inside those ranges, 28G is your calculated size. If you are close but not quite, the sister sizes below will usually have you covered.

How to measure yourself for a 28G

You need a soft tape measure and, ideally, a non-padded bra. Stand up straight and breathe normally — measuring too tight is the most common reason people end up in the wrong size.

• Underbust: wrap the tape snugly around your ribcage directly under the bust, level all the way round. For a 28 band you are looking for roughly 27–28 inches (69–71 cm).
• Bust: measure loosely around the fullest part, tape parallel to the floor. For 28G that is about 35–36 inches (89–91 cm).
• Subtract: bust minus underbust gives you the cup. A gap of about 7–8 inches is the G cup that makes 28G.

How to check the fit is actually right

Numbers get you to the right size on paper; these hands-on checks tell you whether it fits in real life. Do them in front of a mirror, wearing the bra on the loosest hook:

• Band: it should sit level all the way around, in line with the front. Slide two fingers under it at the back — snug, not loose, no riding up when you raise your arms. The band does roughly 80% of the support work, so this matters most.
• Cups: do a quick “scoop and swoop” — lean forward, settle everything into the cup, then stand up. There should be no spillage over the top or sides, and no wrinkling or gaping at the edge. Spillage means size up a cup; gaping means size down a cup.
• Centre gore: the little bridge between the cups should lie flat against your breastbone. If it floats off the body, the cup is usually too small.
• Straps: you should fit a finger under them comfortably. If they dig in or carry most of the weight, the band is too loose — tighten it or size the band down.

28G in international sizing

So a US 28G is written 28F in the UK, 60G across much of the EU and 75G in France. The band number and the cup letter can both change between systems, which is why the same bra can look like two different sizes depending on where it was made.

Sister sizes of 28G

Sister sizes hold the same cup volume as 28G but on a different band — the natural sizes to try when the band feels tight or loose. Here is the 28G sister family:

Common fit problems with a 28G — and how to fix them

• Spillage over the top or sides: if a 28G overflows, the cup is too small for your bust — move up to 28H or try its sister size.
• Straps digging in: in fuller cups the band should carry the weight. If straps bite, the band is too loose — size the band down and the cup up.
• Centre gore floating: common in fuller cups when the cup is a touch small; the bridge should tack flat to the breastbone.
• Band riding up at the back: 28 is a narrow band and can creep up if it is even slightly loose. It should sit level with the front; if it rides up, go down a band and up a cup (a sister size).

Best bra styles for a 28G

For a 28G, look to full-cup and balconette styles with side-support panels, wider straps and underwire for lift and containment. On a narrow band, seek-out brands that cut small bands generously so the wing still feels supportive. Whatever the style, get the band right first — it is the foundation every other part of the fit sits on.

Where to find 28G bras

28G falls outside the core high-street band, so everyday shops may carry fewer options. Specialist fuller-bust or extended-size retailers will have far more choice, and knowing your sister sizes widens what you can wear when a specific size is out of stock.

Is 28G big or small?

28G sits in the full range for cups on a smaller band. Whether that reads as ‘big’ or ‘small’ depends entirely on the band it sits on: the cup volume of 28G is identical to every sister size in the table above, even though the letters differ. That is the single most useful thing to understand about bra sizing — the letter alone tells you very little without the band.

Related sizes and comparisons

• 28DDD vs 28G — one cup smaller on the same band.
• 28G vs 28H — one cup larger on the same band.
• 26H guide — a sister size of 28G.
• 30DDD guide — a sister size of 28G.