6FF Bra Size (AU)
Everything about the 6FF bra size in Australia & New Zealand sizing: what it means, its measurements, whether it runs big or small, sister sizes, and conversions to US, UK, EU & FR.
What is a 6FF bra size?
A 6FF in Australia & New Zealand sizing is a bra with a 6 band and a FF cup. “6” is the Australian band, a dress-size-style number: US band − 22 = 6. “FF” is the cup, from a 8-inch difference between the bust and the band (one inch per cup letter). The same body is written as US 28H, UK 28FF, EU 60H, FR 75H, IT 0H.
Someone who measures roughly 27 inches (69 cm) around the ribcage and about 36 inches (91 cm) around the fullest part of the bust lands at 6FF using the modern snug-measure method. The band carries most of the support; the cup describes the breast volume the bra needs to hold: measured relative to that band.
“6” is the Australian band, a dress-size-style number: US band − 22 = 6. It sets how the bra fits around the ribcage and provides about 80% of the support.
FF is a full-bust cup: a 8-inch bust-minus-band difference. It reflects breast volume, always relative to the 6 band.
Band and cup are one size. A 6FF is not the same volume as a 10FF: the cup letter only has meaning next to its band.
6FF measurements
A 6FF comes from two measurements: a snug underbust that gives the 6 band, and a looser bust. The cup is the gap between the two: for FF, that gap is 8 inches.
| Measurement | Range | Sets |
|---|---|---|
| Underbust (snug) | 26.5–28.4″ · 67–72 cm | Band 6 |
| Bust (fullest) | 35.5–36.4″ · 90–92 cm | — |
| Difference | 8″ · ≈ 20 cm | Cup FF |
Underbust rounds to the nearest even band; an odd reading (e.g. 27″) can go either way, so try 6FF and 6FF and let the band decide.
Measurements vary by body shape, so treat these as the center of a range. AU band labels are converted from the US band by convention rather than read directly in centimeters, which is why a converted size can feel a step different from a bra drafted natively in this system.
Is 6FF big or small?
6FF is a full-bust cup on a petite band: carried by full-bust specialists more than mainstream ranges. But the honest answer is that a cup letter is not a fixed amount of volume: it grows with the band. Tap a size below to see how.
All five are FF cups, yet the volume grows with the band. 6FF is the highlighted size.
Because the cup is measured relative to the band, a 6FF holds more than a 6FF and less than a 14FF, even though all three are “FF cups.” So “big” or “small” only has meaning once you know the band.
If 6FF cups fit well but the band feels off, you don't need a different cup: you need a sister size. And if you're unsure 6FF is your starting size, the calculator settles it from two measurements.
Were you measured as 6FF correctly?
Most people wearing the wrong size were sized by the old “+4 rule”: adding four inches to the underbust to get the band. It inflates the band and, because the cup is the difference from that inflated band, understates the cup by about two letters.
Same body, same volume: the old rule pushes it into a looser band and a smaller cup.
The tell-tale signs you were sized with the old method: the 6 band rides up at the back, you fasten it on the tightest hook from day one, and the straps do most of the work. If that sounds familiar, measure again with a snug tape: it holds the same volume on a band that actually supports.
Key takeaway: if a calculator adds inches to your underbust, its 6FF is not the same 6FF as ours. Brasize.ai uses the modern snug-measure standard used by professional fitters.
Which bra styles fit a 6FF best?
At this depth the bra is doing real load-bearing work. Prioritise full-cup and side-support constructions from full-bust specialists, firm (often three- or four-hook) bands, and wider straps. Molded single-piece cups rarely fit well here; seamed cups distribute weight and shape better. On a petite frame like a 28 band, also look for narrower wires and shorter straps: many mainstream ranges draft their wires for average frames, which is why small-band sizes can feel wide at the side even when the cup volume is right.
Full-cup and side-support constructions from full-bust specialists.
Look for a three-hook band with firm, wide elastic: the band does the lifting.
Narrower wires and shorter straps suit a 6 frame.
Sister sizes share cup volume but not cup shape: the wire on a smaller band is narrower and more projected, the wire on a larger band is wider and shallower. If you have a narrow breast root, the snugger sister will often fit better; if your root is wide, the looser sister may: even when the band tension of the original was right.
6FF sister sizes
Sister sizes hold the same cup volume as 6FF on a different band. They're the fix when the cups fit but the band is too loose or too tight.
| Size | Band feel vs 6FF | Cup volume | When to try it |
|---|---|---|---|
| 6FF | Your starting size | — | Band sits firm and level |
| 8F | One band looser | Same as 6FF | 6 band digs in or feels tight |
| 10E | Two bands looser | Same as 6FF | Rarely right: the band gives up too much support |
The rule: go down a band and up a cup for the same cups on a tighter band, or up a band and down a cup (6FF → 8F) for the same cups on a looser band. Sister sizes share cup volume but not cup shape: the wire on a smaller band is narrower and more projected, the wire on a larger band is wider and shallower. If you have a narrow breast root, the snugger sister will often fit better; if your root is wide, the looser sister may: even when the band tension of the original was right.
Signs 6FF is too small, or too big
Fix: go up a cup on the same band → 6G. If the band is also loose, go to the snugger sister.
Fix: gaping cups → down a cup, 6F. Band riding up with cups that fit → the snugger sister.
6FF in US, UK, EU & FR sizing
The same 6FF body measurements are written differently around the world. Bands and cup letters diverge by region, so convert deliberately when buying from an international brand.
| Region | Size | How the band is derived |
|---|---|---|
| United States (US) | 28H | Band in inches |
| United Kingdom (UK) | 28FF | Same band as US; cups diverge above DD |
| Europe (EU) | 60H | US band × 2.5 − 10 = 60 |
| France / Spain (FR) | 75H | EU band + 15 = 75 |
| Australia / NZ (AU) | 6FF | US band − 22 = 6 |
| Italy (IT) | 0H | (EU − 60) ÷ 5 = 0 |
| Japan (JP) | 60H | EU band; cups close to EU |
| Germany (DE) | 60H | EU sizing |
Cup letters agree across systems up to D. Above D they diverge (a US DDD is a UK E and an EU F) which is where the size converter earns its keep. Brands that size natively in AU: Berlei, Bendon, Bras N Things, Triumph AU.
How to tell if 6FF is your correct size
A calculated 6FF is an accurate starting point. Confirm it on the body: band, cups, gore, straps.
- Band sits firm and level. The 6 band should be snug around your ribcage with room for two fingers, not riding up at the back. It gives most of the support.
- Cups fully contain the breast. No spillage over the top or sides, and no gaping or wrinkling in the FF cups. Gaping usually means down a cup; spillage means up a cup.
- Center gore lies flat. The panel between the cups should sit against your sternum, not float away.
- Straps stay put. If you're tightening straps to feel supported, the 6 band is probably too big.
If the cups fit but the band is wrong, move to a sister size rather than changing cup letters. There's no universal standard between brands: a 6FF in one label can fit like the size on either side in another, so use the fit checks, not just the label. Full symptom-by-symptom guide: bra fit guide.
Educational resource, not medical advice. Read our editorial policy.
HauteFlair labels cups in UK letters, so these links already convert your size by position (a US DDD lands on a UK E, a US G on a UK F). HauteFlair is owned by the same company as Brasize.ai; that relationship never changes the sizing math, charts, or fit advice on this page. How this site makes money.
Is 6FF actually your size?
Don't guess from a label. Enter two measurements and get your accurate size in eight systems, plus your sister sizes.
Calculate My Bra Size →6FF bra size: answered
The questions people ask most about the 6FF size: its volume, sister sizes, conversions and fit.
Is 6FF a big bra size?
6FF is a full-bust cup on a 6 band. A cup letter is a ratio, not a fixed volume: FF means a 8-inch difference between bust and band, so a 6FF holds more than a 6FF and less than a 14FF. “Big” only has meaning once you know the band.
What is the sister size of 6FF?
The sister size of 6FF is 8F (looser band); there is no snugger sister within the standard range because 6FF is already at the edge of the band scale. Sister sizes hold the same cup volume as 6FF on a different band. Move to one when the FF cups fit but the 6 band is too loose or too tight.
What is 6FF in European sizing?
A AU 6FF is an EU 60H. EU bands follow US × 2.5 − 10; cup letters match up to D, then EU continues the alphabet (E, F, G) where the US repeats D.
What is 6FF in UK sizing?
A AU 6FF is a UK 28FF. US and UK share inch bands and agree on cups through DD; above that US DDD = UK E, US G = UK F, US H = UK FF.
What measurements are a 6FF?
Roughly a 27-inch (69 cm) snug underbust and a 36-inch (91 cm) bust at the fullest point. The 8-inch difference gives the FF cup; the underbust gives the 6 band. Treat these as the center of a range.
What is 6FF in centimeters?
A 6FF corresponds to an underbust of about 67–72 cm and a bust of about 90–92 cm: a difference of roughly 20 cm. In metric-labelled systems the same size is EU 60H, FR 75H and JP 60H.
Which bra styles suit a 6FF?
At this depth the bra is doing real load-bearing work. Prioritise full-cup and side-support constructions from full-bust specialists, firm (often three- or four-hook) bands, and wider straps. Molded single-piece cups rarely fit well here; seamed cups distribute weight and shape better. On a petite frame like a 28 band, also look for narrower wires and shorter straps: many mainstream ranges draft their wires for average frames, which is why small-band sizes can feel wide at the side even when the cup volume is right.
How do I know if 6FF is my correct size?
Check four things: the 6 band sits level and snug on the loosest hook, the FF cups are filled without spillage or gaping, the center gore lies flat against the sternum, and the straps stay put without carrying the weight. If the band is wrong but the cups fit, try a sister size.