Reviewed
40K (UK 40H) bra size
A 40K has a 40-inch band and a K cup, about 11 inches between band and bust. In the UK it is 40H, in Australia 18H and in Europe 90K.
- US
- 40K
- UK
- 40H
- AU
- 18H
- EU
- 90K
- FR
- 105K
Also fits (sister sizes): 38L firmer band · 42J looser band · all same-volume sizes ↓
40K measurements
- Snug underbust
- 40–41 in · 102–104 cm
- Bust, fullest part
- about 51 in · 128–131 cm
- Cup difference
- 11 in (K cup)
These are starting points from the band-and-cup method. Brands differ by about a size, so a two-minute measurement beats any chart.
40K sister sizes
Same cup volume, different band. If a 40K band feels too loose, go down a band and up a cup; if it feels tight, go up a band and down a cup.
If a 40K doesn't fit
Not sure what's wrong? Run through the 4-point fit check.
40K questions
What is the sister size of 40K?
38L (one band down, one cup up) and 42J (one band up, one cup down). Sister sizes hold the same cup volume on a different band.
What is 40K in UK, Australian and European sizes?
UK 40H, Australia 18H, Europe 90K and France 105K. US and UK cup letters match up to DD and then split.
What measurements are a 40K?
A snug underbust of about 40–41 in (102–104 cm) and a bust of about 51 in (128–131 cm). Measure with the tape level and use the calculator for an exact result.
Is 40K a big size?
40K has a very full cup volume for a 40 band. Cup letters only mean something next to the band: a 40K holds the same as 32O or 34N.