Bra size calculator: find her size, or yours
Work out a bra size in 3 steps from a bra tag, her clothes size, her build or two tape measurements. You get the size in US, UK, Australian and European sizing, its sister sizes and safe gift picks. Free, and your answers never leave your phone.
- Method
- Details
- Size
What have you got to go on?
Her size in every system
"Also fits" sizes hold the same cup volume on a firmer or looser band. Try one if the band feels wrong but the cups fit. EU and FR sizes here are converted from the UK size.
Safe buys at this confidence
Where is the size on a tag?
On the back band near the hooks, or on the side seam. Many tags list several countries in a row: pick the line for the country where it was bought. No tag? Try another bra she wears often, or switch to Her clothes.
Clothes sizes measure her whole body, not her bust, so this gives a range. Good enough for bralettes and sleepwear.
Under the bust, snug
Around the fullest part, loose
Leaning forward, fullest part, loose
What is my bra size? How the calculator works
- Pick what you know. A bra tag that fits well, a clothes size, a body shape, or a tape measure. Each method shows how reliable it is before you start.
- Set the details. Drag the tapes or tap the options. The size updates as you go, in US, UK, AU or EU sizing.
- Get the size. You see the bra size, its sister sizes, every country's equivalent and what to buy at that confidence.
How it helps
- Buying a gift? Find her bra size without asking, then pick something safe for the confidence you have. Keep it with her ring, dress and shoe sizes on her size card.
- Measuring yourself? Two measurements give an exact bra size; the how to measure bra size guide shows each step.
- Between sizes or brands? Sister sizes and the bra size converter show what else fits.
Every size on one chart
Her size is marked in ink. The yellow diagonal is her sister sizes: same cup volume, different band. Tap any size to read it.
How sure is each method?
- Eyeballing1/10Almost always wrong. A 30E holds far less than a 38E, so cup letters can’t be judged by eye.
- Her clothes size3/10Shows her frame, not her bust. Use it for bralettes, robes and pyjamas.
- Her build4/10A sensible range when you have nothing else to go on.
- A bra tag8/10Good, if she likes how that bra fits. Many women wear the wrong size.
- Measuring together10/10Exact. Two measurements, about a minute.
Reading her bra tag
- Look on the back band or the side seam near the hooks. Many women cut tags out, so check a few bras.
- Find the line for your country. One tag often lists US, UK, EU and FR sizes side by side.
- Pick a bra she wears often. A favourite is more likely to be the right size than one in the back of the drawer.
The 4-point fit check
- BandLevel all the way round and firm on the loosest hook. If it rides up at the back, go down a band.
- CupsNo spilling over the top and no gaping. Spill means cups too small; wrinkles mean too big or the wrong shape.
- CentreThe middle part between the cups lies flat on her chest.
- StrapsTwo fingers fit underneath. They shouldn’t dig in or slip off.
Guides
Sizing basics
How bra sizes work, how to measure, and every country's sizes.
- How Do Bra Sizes Work? Band, Cup and Country Explained
- Bra Cup Letters Explained: What A, B, C and DD Really Mean
- Sister Size Chart: Bra Sizes With the Same Cup Volume
- What Is the Biggest Bra Size? Why the Band Decides
- Average Bra Size in the US and UK, and Why It Misleads
- Is 34C Big? How to Tell if a Bra Size Is Big
- Bra Size Chart: Every Band and Cup in US, UK, AU, EU and FR
- Every Bra Size, A to K
- What Is a B Cup? Size, Measurements and Sister Sizes
- What Is a C Cup? Measurements, Volume and Sister Sizes
- What Is a D Cup? Is It Big? Measurements by Band
- What Is a DD Cup? DD vs E and Sizes by Band
- What Is an E Cup? UK, US and EU E Explained
- How to Measure Bra Size at Home in Two Measurements
- How to Measure Bra Size Without a Tape Measure
- How to Measure Bra Size Without a Bra (Soft or Settled Breasts)
- Printable Measuring Tape
- UK Bra Size Calculator
- Australian Bra Size Calculator
- Bra Size Conversion Chart for US, UK, AU, EU and FR
- Bra Size in CM: Measure in Centimeters and Read EU Sizes
- UK to US Bra Size Converter and Guide
- US to UK Bra Size Converter and Guide
- Australian Bra Size Conversion to US, UK and EU
- International Bra Size Conversion: EU and French Sizes
Fit by body
Fit checks and bras for different breast shapes.
By outfit
What to wear under backless, strapless and sportswear.
- Types of Bras: Nine Styles and What Each One Is For
- Bralette Size Chart: Bra Size to S, M, L and XL
- What Bra to Wear With a Halter Top
- What Bra to Wear With Off-the-Shoulder and One-Shoulder Tops
- What Bra to Wear Under a White Shirt
- What Bra to Wear With a Backless Dress
- Bra for a Strapless Dress: Size and Fit Guide
- Sports Bra Size Chart: XS to XXL by Band and Cup
- Types of Sports Bras: Compression, Encapsulation and More
Bra care
Washing, storing and knowing when to replace a bra.
Buying for her
Find her size without asking, and gifts that forgive a guess.
- How to Buy Lingerie for Your Wife or Girlfriend
- How to Find Out Her Bra Size From the Tag
- Bra Size From Dress Size: What Her Clothes Can and Cannot Tell You
- How to Guess Bra Size From Body Shape, and When Not To
- How to Measure for Bra Size Together
- Lingerie Gift Ideas When You Don't Know Her Size
- Buying Lingerie for Christmas: How to Get Her Size Right
- Her Size Card
Questions men actually ask
Can I work out her bra size without asking her?
Yes, roughly. The best way is the tag on a bra she likes. Her clothes size or build gives a range, which is fine for bralettes and sleepwear but risky for an underwired bra.
What if she cut the tags out?
Very common, because tags itch. Use her clothes size or build for a range, then pick something with stretch, or give a gift card with a small item.
Is a D cup big?
Not on its own. The cup letter only means something next to the band: a 30D holds about the same as a 34B.
Why do UK and US sizes differ?
Bands match. Cups match up to DD, then the UK goes E, F, FF, G while the US goes DDD, G, H, I.
Do you store my answers?
No. The calculator runs in your browser. A shared link carries only the size, in the part of the address that is never sent to our server.