Bra Size Calculator
Two measurements, a few seconds, and your UK band and cup size. Then go straight to bras in your exact fit, with sister sizes for any brand that runs a little tight or loose.
Snug, level, directly under your bust. Breathe out before reading.
Relaxed tape across the fullest part of your bust.
Your recommended UK starting size
A starting point for trying on. Fit varies between brands and styles.
How to Measure Your Bra Size
You need a soft tape measure and a mirror. Measure in a non-padded bra or none at all, never over a padded one. Take each measurement twice and use the average.
Band: the underbust
- Wrap the tape directly under your bust, where the band of a bra sits.
- Keep it firm and level all the way around your back.
- Breathe out fully, then read the number.
- This sets your band size, the 30, 32, 34 and so on.
Cup: the bust
- Stand upright and measure across the fullest part of your bust.
- Keep the tape relaxed and level, not lifted at the back.
- Lean forward slightly first if it helps the tissue settle.
- The gap between this and your band measurement sets your cup.
The calculator above does the maths for you. The cup is worked out from the difference between your bust and your band size, which is how UK cups are graded, so you get a more accurate result than a rough bust-minus-underbust sum.
UK Bra Cup Size Chart
UK cups step up roughly one inch at a time. This is the difference between your bust and band measurement.
Sister Sizes Explained
If your calculated size is close but not quite right, a sister size has the same cup volume in a different band. Go down a band and up a cup for a firmer fit, or up a band and down a cup for a looser one. The cup letter changes but the actual cup stays the same size.
Band feels too tight
Try one band up and one cup down. A 34D becomes a 36C. Same cups, more room around the body.
Band feels too loose
Try one band down and one cup up. A 34D becomes a 32DD. Same cups, a firmer, more supportive band.
Why it matters
Brands run differently. Knowing your sister sizes means a style that does not stock your exact size is still an option.
How a Well-Fitting Bra Should Feel
The band
Level all the way round and firm on the loosest hook when new. It does most of the support work, not the straps.
The cups
They should fully contain the bust with no spillage and no gaping. Wires sit flat against the ribcage.
The straps
Supportive but not carrying the weight. They should not dig in or leave deep marks by the end of the day.
The centre
The gore between the cups should sit flat against your breastbone, not float away from the body.
Common Questions
How accurate is a bra size calculator?
A calculator gives a reliable starting size from your measurements, but it cannot judge breast shape, tissue softness or how a particular brand is cut. Treat the result as the first size to try on, then adjust using sister sizes if the fit is close but not perfect.
Should I measure in a bra or without one?
Measure in a non-padded, non-push-up bra or with no bra at all. A padded bra adds to the bust measurement and will push your result towards a cup size that is too large.
My size came out different from another shop. Why?
Older fitting methods added four or five inches to the underbust to find the band, which tends to give a band too big and a cup too small. Modern UK fitting, which this calculator uses, takes the snug underbust measurement directly. If two shops disagree, trust the fit on your body over the number on the label.
How often should I check my bra size?
Body shape changes with weight, age, pregnancy and hormones, so it is worth remeasuring every six to twelve months, or sooner if your current bras have started to feel different.
What is the difference between band size and cup size?
The band size is the number, taken from the measurement under your bust, and it provides most of the support. The cup size is the letter, worked out from how much bigger your bust is than your band. A full bra size is the two together, such as 34DD.
Uplifted Lingerie is a specialist UK bra retailer stocking band sizes 28 to 48 and cups A to L from brands including Fantasie, Freya, Elomi, Panache and Curvy Kate. Once you have your size, every band and cup has its own page so you can shop your exact fit.