Skip to content
Bra Size
Size
Bra Size
Find My Size

Free bra size calculator A better fit starts here.

Find a suggested starting bra size, understand what it means, and learn what to check when you try a bra on.

  • Free to use
  • No account needed
  • Inches or centimeters

Find your starting size

Enter your measurements to get a suggested starting size.

Measurement unit
in
Measure around your ribcage, directly below your bust.
in
Measure around the fullest part of your bust, without pulling tight.

Your result is a starting point. Brand, style and shape can affect the fit. Measurements are calculated in your browser and are not sent or saved.

How our sizing method works

How to Measure

Take two level measurements with a soft tape, standing relaxed, either without a bra or in a non-padded bra.

Diagram of an upper torso: measure the underbust directly below the bust, and the bust around its fullest part Bust Underbust
  1. 1

    Underbust

    Wrap the tape snugly around your ribcage, directly below your bust where a bra band sits. Keep it level and breathe out normally.

  2. 2

    Bust

    Measure around the fullest part of your bust, keeping the tape level and relaxed so it does not press in.

Tip: Enter the number you read from the tape. Do not add inches to your underbust; the calculator handles rounding.

Read the full measuring guide
How it works

From measurements to a more confident fit

See the measuring guide
  1. 01

    Measure

    Measure your underbust and bust with a soft tape, keeping it level and relaxed.

  2. 02

    Understand

    Get a suggested starting size and see how the band and cup were worked out.

  3. 03

    Check the fit

    Try a bra on and check the band, cups and straps with our fit checker.

Fitting tools

Useful tools for your next fitting question

Sister Size Calculator

Compare nearby sizes when the band needs adjusting but the cups fit.

Find your sister sizes

International Size Converter

Convert bra sizes between US, UK, EU, French and Australian labels.

Convert a bra size

Bra Fit Checker

Work through common band, cup and strap problems to see what to check next.

Check how your bra fits

Bra Size Chart

See how band numbers and cup letters work together in each sizing system.

Open the size chart
Diagram of an upper torso: measure the underbust directly below the bust, and the bust around its fullest part Bust Underbust
  • Bust: fullest part, tape relaxed
  • Underbust: directly below the bust, snug
Start with your measurements

A little guidance makes measuring easier.

Follow the tape-position illustrations, check your units, and take your time before entering your measurements.

  • Find the correct tape position.
  • Keep the tape level all the way round.
  • Check your numbers before calculating.

Something doesn’t feel right?

Start with what you notice.

My band rides up

Often a band that is looser than it needs to be, though straps and wear can cause it too. Troubleshoot band

My cups gape

Can mean the cup is too large, or that the cup shape does not match yours. Troubleshoot cups

My cups overflow

Usually a cup that is too small, or a style with less coverage than you need. Troubleshoot overflow

My straps slip

Strap length, a band that rides up, or straps set wider than your shoulders. Troubleshoot straps

Fit problems can have more than one cause. The fit checker helps you decide what to check next.

Open the Fit Checker
Shapes and styles

Explore bra shapes and styles

Understand differences in coverage, construction and everyday use across balconette, plunge, full-cup and more.

Rows of colorful bras hanging on strings
Explore styles
Brand sizing

Understand sizing by brand

Check which sizing system a brand uses before you shop, with links to each brand’s official size guide.

A blank white tag hanging from a red garment
Browse brand size guides
Shopping next step

Ready to explore bras in your size?

Use your starting size to explore styles and retailer options. Always confirm the retailer’s size chart and availability before you buy.

Find Bras Bra Buying Guides
Guides

Bra size, style and care guides

Bra sizes

All bra sizes

Bra styles

All bra styles

Bra care

All bra care

Buying guides

All buying guides
Our method

Clear guidance, with the method explained

Understand the calculation

See exactly how measurements become a starting size, using a published UK method with no inches added to the band.

Know the limitations

A two-part size label cannot describe breast shape, and brands differ. We explain where the method stops.

Help improve the guidance

Tell us when an instruction or result looks wrong. Corrections are reviewed and the method page is updated.

Read how our calculator works
Common questions

Frequently asked questions

How accurate is a bra size calculator?

A calculator gives a starting point, not a guaranteed fit. Breast shape, the style of bra and differences between brands all affect how a size fits, and research has found tape-based methods often differ from a professionally fitted size. Try the suggested size, then use the fit checker.

Should I measure in inches or centimeters?

Either works. US and UK band sizes are based on inches, so centimeter measurements are converted to inches (1 inch = 2.54 cm) before the same rules are applied. Use the same unit for both measurements.

Do I add 4 inches to my band size?

No. The method we use takes your underbust as measured, rounds it up to a whole inch and then to an even number. Adding 4 or 5 inches is an older method that tends to give a looser band and a smaller cup.

What are sister sizes? Is a 34DD the same as a 36D?

Sister sizes have approximately comparable cup capacity on a different band. 34DD and 36D are sister sizes: the 36D has a looser band. They are options to try, not exact equivalents. Use the sister size calculator.

Are UK and US bra sizes the same?

Band numbers match, and cups usually match up to DD. Above that they differ: for example, a UK E is usually a US DDD and a UK F is usually a US G. Use the bra size converter and check the brand’s own chart.

Why does the suggested size differ from my current bra?

Your current size may have been chosen with a different method, a different brand, or a bra that has stretched. The calculator does not add inches to your band, which can give a smaller band and a larger cup letter than you are used to. Fit is what matters, so try the size and check it.

Which is bigger, 34C or 36C?

A 36C has a larger band and, because cup size is graded with the band, a larger cup than a 34C. Cup letters only make sense alongside the band; see the bra size chart.

Does bra size change with age or weight?

It can. Changes in weight, pregnancy, breastfeeding and menopause can all change size and shape, so it is worth re-measuring and re-checking fit from time to time.