Reviewed
40I (UK 40G) bra size
A 40I has a 40-inch band and a I cup, about 9 inches between band and bust. In the UK it is 40G, in Australia 18G and in Europe 90I.
- US
- 40I
- UK
- 40G
- AU
- 18G
- EU
- 90I
- FR
- 105I
Also fits (sister sizes): 38J firmer band · 42H looser band · all same-volume sizes ↓
40I measurements
- Snug underbust
- 40–41 in · 102–104 cm
- Bust, fullest part
- about 49 in · 123–126 cm
- Cup difference
- 9 in (I 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.
40I sister sizes
Same cup volume, different band. If a 40I 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 40I doesn't fit
- Band rides up at the back
- Try 38J
- Band digs in, cups fit
- Try 42H
- Spilling over the cups
- Try 40J
- Cups gape or wrinkle
- Try 40H
Not sure what's wrong? Run through the 4-point fit check.
40I questions
What is the sister size of 40I?
38J (one band down, one cup up) and 42H (one band up, one cup down). Sister sizes hold the same cup volume on a different band.
What is 40I in UK, Australian and European sizes?
UK 40G, Australia 18G, Europe 90I and France 105I. US and UK cup letters match up to DD and then split.
What measurements are a 40I?
A snug underbust of about 40–41 in (102–104 cm) and a bust of about 49 in (123–126 cm). Measure with the tape level and use the calculator for an exact result.
Is 40I a big size?
40I has a very full cup volume for a 40 band. Cup letters only mean something next to the band: a 40I holds the same as 28O or 30N.