How do I measure my bra size in the UK?

Use a soft tape measure. Measure your underbust (directly under your breasts) to get your UK band size. Then measure loosely around the fullest part of your chest for the bust. Subtract band from bust — each inch of difference equals one UK cup size: 1=A, 2=B, 3=C, 4=D, 5=DD, 6=E, 7=F, and so on.

What is a UK DD cup compared to a US DD?

A UK DD and a US DD are the same cup size. Both represent a 5-inch difference between band and bust. The cup systems diverge after DD: a UK E equals a US DDD or F, and a UK F equals a US G. Always check the brand's country of origin when shopping internationally.

What are sister sizes in UK bra sizing?

Sister sizes in UK bra sizing are sizes that share the same cup volume on different band widths. For example, 32E, 34D, and 36C are UK sister sizes — they all hold the same breast volume. Go up one band and down one cup letter, or down one band and up one cup letter, to find yours.

What is a 34D in UK sizing equivalent to in EU sizing?

A UK 34D is equivalent to an EU 75D. UK band size 34 converts to EU band size 75 (approximately 34 inches × 2.54 = 86 cm, rounded to nearest 5 = 85–90 cm). Cup letters are the same up to D in both systems.

How is UK bra sizing different from US bra sizing?

UK and US bra sizes use the same numeric band sizes but differ in cup letter progression after DD. UK cups continue: DD, E, F, FF, G, GG, H, HH. US cups continue: DD, DDD/F, G, H, I, J. A UK 34E is roughly equivalent to a US 34DDD. Always check conversion charts when buying from US brands.

Why does my UK bra band ride up at the back?

A bra band riding up at the back usually means the band size is too large. In UK sizing, go down one band size and up one cup letter to keep the same volume (e.g. from 36C to 34D). Also ensure you are fastening the bra on its loosest hook when new, moving to tighter hooks as it stretches.

How do I convert my UK bra size to EU sizing?

To convert a UK bra size to EU sizing, multiply your UK band size in inches by 2.54 and round to the nearest 5 to get the EU band in centimetres (e.g. 34 × 2.54 ≈ 86, rounds to 85 cm = EU 85). Cup letters are mostly the same up to D; after that, EU uses E where UK uses E, and they generally align closely.

How often should I remeasure my UK bra size?

Remeasure every 1–2 years, or whenever your bras feel uncomfortable. Weight changes, pregnancy, breastfeeding, menopause, and hormonal fluctuations can all shift your measurements by a full UK size or more. Many UK lingerie retailers such as Marks & Spencer and John Lewis offer free in-store fittings.

🇬🇧 UK Sizing Standard

UK Bra Size Calculator
Find Your Perfect British Fit

Enter your underbust and bust measurements below — in inches or centimetres — and get your exact UK bra size instantly, including sister sizes and personalised fit advice.

2measurements needed

12+UK cup sizes covered

100%free to use

Underbust (band) Snugly under bust, tape level all around

Fullest bust Loosely across fullest point, don't compress

Calculate Enter both numbers and press the button

Underbust — band size UK

Fullest bust

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Your UK bra size

UK band size

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UK cup size

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Difference

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UK cup scale — your size highlighted

Equiv. sizes

UK sister sizes — same cup volume, different band

UK fit tip

UK Bra Size Chart

Complete UK cup sizes by underbust-to-bust difference, with international conversions

UK cup sizes by underbust-to-bust difference in inches
Difference (in)	UK Cup	Example UK Size	US Equivalent	EU Equivalent
0–½"	AA	34AA	AA	AA
1"	A	34A	A	A
2"	B	34B	B	B
3"	C	34C	C	C
4"	D	34D	D	D
5"	DD	34DD	DD	E
6"	E	34E	DDD / F	F
7"	F	34F	G	G
8"	FF	34FF	H	H
9"	G	34G	I	I
10"	GG	34GG	J	J
11"	H	34H	K	K
12"	HH	34HH	L	L

UK band sizes by underbust measurement
Underbust (in)	UK Band	Underbust (cm)	EU Band (cm)
22–23"	24	56–59 cm	55
24–25"	26	60–63 cm	60
26–27"	28	64–68 cm	65
28–29"	30	69–73 cm	70
30–31"	32	74–79 cm	75
32–33"	34	80–84 cm	80
34–35"	36	85–89 cm	85
36–37"	38	90–94 cm	90
38–39"	40	95–99 cm	95
40–41"	42	100–104 cm	100
42–43"	44	105–109 cm	105
44–45"	46	110–114 cm	110

UK to EU bra size conversion chart
UK Size	EU Band	EU Full Size	Notes
28D	60	60D	Same cup letter
30D	65	65D	Same cup letter
32D	70	70D	Same cup letter
34D	75	75D	Same cup letter
36D	80	80D	Same cup letter
34DD	75	75E	UK DD = EU E
34E	75	75F	UK E = EU F
34F	75	75G	UK F = EU G
34FF	75	75H	UK FF = EU H
34G	75	75I	UK G = EU I

UK to US bra size conversion chart
UK Size	US Equivalent	Cup difference	Notes
34A	34A	None	Identical up to D
34B	34B	None	Identical up to D
34C	34C	None	Identical up to D
34D	34D	None	Identical up to D
34DD	34DD	None	Both use DD
34E	34DDD / 34F	+1 UK letter	UK E = US DDD
34F	34G	+1 UK letter	UK F = US G
34FF	34H	+1 UK letter	UK FF = US H
34G	34I	+1 UK letter	UK G = US I
34GG	34J	+1 UK letter	UK GG = US J

Definition

A UK bra size calculator converts your underbust and bust measurements into a British-standard bra size, expressed as an even number (band) and a letter or double-letter (cup). UK cup sizing uses a unique progression — AA, A, B, C, D, DD, E, F, FF, G, GG, H, HH — which differs from US sizing after the DD cup.

How UK Bra Sizing Works

UK bra sizing is based on two measurements: the underbust (for the band) and the fullest bust (for the cup). The band size is the underbust measurement rounded up to the nearest even number — so a 31-inch underbust gives a UK 32 band, and a 33-inch gives a UK 34 band.

The cup size is determined by subtracting the band measurement from the bust measurement. Each inch of difference corresponds to one UK cup size, using the British progression of letters. This is where UK sizing diverges from US sizing — particularly at and above a DD cup.

"UK bra sizing after DD cup uses E, F, FF, G, GG, H — not DDD or G as in US sizing. Always check the brand's country when buying online."

UK cup letter progression explained

1 inch difference = A cup
2 inches = B cup
3 inches = C cup
4 inches = D cup
5 inches = DD cup (same as US DD)
6 inches = E cup (US calls this DDD or F)
7 inches = F cup (US calls this G)
8 inches = FF cup (US calls this H)
9 inches = G cup (US calls this I)

UK vs US vs EU Bra Sizing — Key Differences

The most common source of confusion when shopping across borders is the divergence of cup letters after DD. UK and EU sizing both use E for a 6-inch difference; US sizing uses DDD or F. UK uses FF for an 8-inch difference; most other systems use H. Always check the conversion table above when buying from non-UK brands.

Band sizes are also calculated slightly differently. In EU sizing, bands are expressed in centimetres (60, 65, 70, 75, 80...) rather than inches. A UK band 34 corresponds to EU band 75. The converter built into the result panel above handles this automatically.

Sister Sizes in UK Bra Sizing

Sister sizes work identically in UK sizing as in any other system: going up one band size and down one cup letter preserves the same cup volume. This is useful across UK retailers because brand sizing varies — even between Marks & Spencer, ASOS, and Bravissimo, a 34D may fit differently.

If a UK 34D fits in cup volume but the band is slightly loose, try a 32E. If the band is tight, try a 36C. All three contain the same breast volume in the UK system.

Common UK Bra Fitting Mistakes

Using the old "add 4 inches" rule: This outdated method was developed for rigid vintage bras and consistently leads to too-large a band. Measure your actual underbust.
Treating UK and US labels as identical: After DD cup, UK and US cup letters diverge significantly. A UK 34F is not the same as a US 34F.
Buying by label size across UK brands: Sizing varies between Marks & Spencer, Next, Debenhams, Bravissimo, and ASOS. Use your measurements, not the label.
Ignoring the band: The band provides 80% of a bra's support. If the band rides up at the back, it is too large — not too tight.
Never remeasuring: UK women's bodies change with weight, age, pregnancy, and hormonal cycles. Remeasure every 1–2 years.

Frequently Asked Questions

Common questions about UK bra sizing, measurement, and fit

UK Bra Size CalculatorFind Your Perfect British Fit