Skip to main content

♥ Free UK sizing tools

My Bra Size
My Bra Size

Measuring guide

How to measure your bra size

You need a soft tape measure, a mirror and about two minutes. Here is where to place the tape, how to round the numbers, and what they tell you.

Sources checked

A pink bra beside a tape measure, an open notebook and a pencil

What you need

  • A soft fabric tape measure, not a metal one
  • A mirror, to check the tape is level at the back
  • No bra, or one without padding

Step 1

Measure your underbust

Wrap the tape around your ribcage, right where your bust meets your body. Keep it level all the way round and pull it snug. Brastop’s guide says the tape should be “snug but not too tight – enough to get two fingers underneath”.

Breathe out normally and read the number at the front. Note it down, including any half inch.

Underbust Snug and level, right under the bust

Step 2

Measure your bust

Measure around the fullest part of your bust, keeping the tape level and relaxed rather than tight. Brastop suggests bending forward slightly “so that your bust falls forward”, which helps you find the fullest point.

Read the number at the front and note it down.

Bust Relaxed and level, across the fullest part

Step 3

Turn the numbers into a UK size

This is the method Brastop and Boux Avenue publish. Our calculator does the same steps for you.

  1. Band: round your underbust up to a whole inch. If that number is odd, round up again to the next even number. Do not add anything.
  2. Bust: round to the nearest whole inch. A half rounds up.
  3. Cup: take the band away from the rounded bust. Each inch of difference is one cup step: 1 is A, 2 is B, 3 is C, 4 is D, 5 is DD, 6 is E, and so on.

Worked example

In inches
Underbust 31.5 → 32 (already even)
Bust 36.2 → 36
36 − 32 = 4 → D cup
UK 32D
In centimetres
Underbust 80 cm = 31.5 in → 32
Bust 92 cm = 36.2 in → 36
36 − 32 = 4 → D cup
UK 32D
32: the band
Your underbust in inches, rounded up to an even number. When the bra is on, the band should sit firm and level around your ribcage.
D: the cup
How much larger your bust is than the band, at roughly one cup step per inch. UK cups use double letters: D, DD, E, F, FF, G, GG, H and so on.
How to read UK size 32D: 32 is the band, D is the cup.

Inches or centimetres?

UK bra sizes are based on inches. We could not find a UK brand or retailer that publishes a centimetre table for UK bands, so we convert centimetres to inches (1 inch is 2.54 cm) and then apply the same rules. Your result is the same whichever unit you measure in.

European size labels, such as 70D, are a different system. To read one of those, use the bra size converter rather than measuring again.

Common measuring mistakes

  • The tape rises at the back Check in a mirror that the tape is level all the way round. A tape that slopes up at the back gives a smaller number.
  • Pulling the bust tape tight The bust measurement should be relaxed. A tight tape flattens the bust and gives a smaller cup.
  • Adding inches to the underbust Some US charts add 4 or 5 inches to the band. UK retailers that publish a tape method say not to add anything.
  • Measuring over a padded bra Padding adds to the bust measurement. Measure without a bra, or in one without padding.
  • Rounding the underbust down The UK method always rounds the underbust up to a whole inch, then up again to an even number if needed.

When a tape measure is not the best guide

A tape cannot see shape. Brastop says that “two people who have the same measurements may well need two completely different sizes depending on their unique shapes”, and Bravissimo’s fitters do not use tape measures at all. A UK study of 45 women (White and Scurr, 2012) found the traditional tape method tended to give too large a band and too small a cup.

So use your measurements to find a size to try, then judge the fit. The bra fitting guide explains what to check.

Ready? Enter your measurements

The calculator applies the three steps above and shows its working.

How would you like to start?

Find a starting size from your measurements

  1. 1 Underbust
  2. 2 Bust
  3. 3 Your size

Units

Measure snugly around your ribcage, directly under your bust, keeping the tape level.

in
How to measure

Your measurements stay on this page. We do not store them, put them in web addresses or send them anywhere.

Measuring questions

Should I measure with or without a bra?
Either works, as long as any bra you wear has no padding. Padding adds to the bust measurement and can push the result up a cup or more.
How tight should the underbust tape be?
Snug, but not digging in. Brastop suggests leaving enough room to slide two fingers under the tape. Keep it level and breathe out normally.
Can I measure my bra size in centimetres?
Yes. Measure in centimetres and choose centimetres in the calculator. UK sizes are based on inches, so we convert at 2.54 cm to the inch before applying the UK rules.
Why does my measured size differ from the size I wear?
Tape measurements cannot account for breast shape or how a style is cut. Treat the result as a size to try, and use the fit checks to adjust.

Sources

Checked . Brands change their charts, so check the retailer’s own size guide before you buy.

  1. S1 Brastop: How to measure your bra size (opens in a new tab) Tape method; inches-to-cup table (A to K); rounding rules
  2. S4 Boux Avenue: How to measure bra size (opens in a new tab) Tape method; worked example 39 − 34 = 5 (DD); sister sizes; limits of measuring
  3. S17 Bravissimo: Bra fitting guide (opens in a new tab) Fitting without a tape measure; sister-size logic
  4. S26 White & Scurr, Ergonomics 55(6), 2012: Evaluation of professional bra fitting criteria for bra selection and fitting in the UK (opens in a new tab) Tape methods compared with professional fitting

Next steps