UK Bra Size Calculator - Find Your Perfect Fit Free
Free UK bra size calculator to find your perfect fit. Measure your band and bust to get accurate UK bra sizes. Convert US, EU & UK sizes instantly with our fitting guide.
🔢 Calculator
🔢 Calculator
Find your perfect UK bra size in seconds. Enter your measurements and get instant results with international size conversions.
📏 Enter Your Measurements
📋 Your Results
👯 Sister Sizes
Sister sizes have the same cup volume but different band sizes. If your calculated size doesn't feel right, try these alternatives:
How to Measure Your Bra Size Correctly
Wear a non-padded bra or go braless. Wrap a soft measuring tape snugly around your ribcage, directly under your bust. Keep the tape level all around. Round to the nearest inch or centimeter.
Wrap the tape around the fullest part of your bust, usually at nipple level. Keep the tape straight and don't pull too tight. The tape should sit comfortably against your skin.
Enter both measurements in our converter above. The difference between your bust and band measurements determines your cup size. Each inch of difference equals one cup size.
UK Bra Size Chart
The UK uses a letter-based cup sizing system. Here's how band and cup sizes work together:
| Difference (inches) | UK Cup Size | US Equivalent | EU Equivalent |
|---|---|---|---|
| 1" | A | A | A |
| 2" | B | B | B |
| 3" | C | C | C |
| 4" | D | D | D |
| 5" | DD | DD/E | E |
| 6" | E | DDD/F | F |
| 7" | F | G | G |
| 8" | FF | H | H |
| 9" | G | I | I |
| 10" | GG | J | J |
| 11" | H | K | K |
| 12" | HH | L | L |
| 13" | J | M | M |
| 14" | JJ | N | N |
| 15" | K | O | O |
Understanding UK Bra Sizing
The uk bra size calculator computation follows established formulas verified against authoritative sources. Input your values to begin.
A UK bra size consists of two components: the band size (a number) and the cup size (a letter). The band size represents the circumference of your ribcage in inches, while the cup size indicates the volume of your bust relative to your band measurement.
For example, in a size 34D:
- 34 = Your band measurement (around your ribcage)
- D = 4-inch difference between your bust and band measurements
The UK sizing system includes double letters (DD, FF, GG, HH, JJ) which provide more precise sizing options for fuller busts. This is one reason UK bras are popular for D+ cup sizes.
While UK and US band sizes are identical, cup sizes diverge significantly after D cup. The main differences are:
- UK uses double letters: DD, FF, GG, HH, JJ, KK
- US uses triple letters or skips: DDD, DDDD (or jumps to letters)
- UK E = US DDD (a common conversion point)
- There is no UK "I" cup to avoid confusion with lowercase L
Your UK band size should match your underbust measurement rounded to the nearest even number. If you measure 31 inches, your band size would be 32. If you measure 33 inches, your band size would be 34.
A properly fitted band should feel snug on the loosest hook. As the elastic wears over time, you can move to the tighter hooks to maintain support.
To find your UK cup size, subtract your band measurement from your bust measurement. Each inch of difference corresponds to a cup size:
- 1 inch difference = A cup
- 2 inches = B cup
- 3 inches = C cup
- 4 inches = D cup
- 5 inches = DD cup
- 6 inches = E cup
- 7 inches = F cup
- And so on...
Sister sizes are bra sizes that share the same cup volume but have different band sizes. For example, 32D, 34C, and 36B are all sister sizes—they have the same cup volume, just distributed differently.
This is useful if:
- Your calculated band size feels too tight (go up a band, down a cup)
- Your calculated band size feels too loose (go down a band, up a cup)
- You're between sizes in a particular brand
The band rides up in the back: The band is too loose. Try a smaller band size with the next cup size up.
The straps dig into your shoulders: You might need a larger band size, or your straps need adjusting. Most support should come from the band, not the straps.
Spillage over the cups: The cups are too small. Go up one or two cup sizes while keeping the same band.
Gaps in the cups: The cups are too big. Go down a cup size or try a different style that suits your breast shape better.
The underwire pokes: The cup size might be wrong, or the bra style doesn't suit your shape. The underwire should sit flat against your ribcage and not on any breast tissue.
International Bra Size Conversion Guide
Shopping for bras from different countries can be confusing due to varying sizing systems. Here's a comprehensive guide to converting between UK, US, EU, and other international sizes.
Band sizes are the same in UK and US systems. For cup sizes:
- UK A-D = US A-D (identical)
- UK DD = US DD or E
- UK E = US DDD or F
- UK F = US G
- UK FF = US H
- UK G = US I
- UK GG = US J
- UK H = US K
EU band sizes are approximately your underbust measurement in centimeters. To convert UK band to EU, add 4 and multiply by 2.5:
- UK 30 = EU 65
- UK 32 = EU 70
- UK 34 = EU 75
- UK 36 = EU 80
- UK 38 = EU 85
- UK 40 = EU 90
EU cup sizes generally follow the same letter sequence as UK sizes.
Australian sizing is similar to UK sizing but typically 2 inches smaller in band size:
- UK 30 = AU 8
- UK 32 = AU 10
- UK 34 = AU 12
- UK 36 = AU 14
- UK 38 = AU 16
Cup sizes are the same between UK and AU.
French sizing is the same as EU sizing. Add 4 to your UK band size and multiply by 2.5.
Expert Tips for Uk Bra Size Calculator
Don't just note the number - make sure you understand what your Uk Bra Size Computer result means for your specific situation.
When sharing your Uk Bra Size Tool calculation with others, include context about what inputs you used.
If you'll need Uk Bra Size Computer calculations again, bookmark this page for quick future access.
Before calculating, double-check your Uk Bra Size Calculator values. A small typo can significantly change your result.