Discover your perfect fit with the UK’s most accurate bra size calculator! Designed specifically for British bodies and brands like M&S and Bravissimo, our free tool eliminates guesswork by using professional fitting methods—no outdated ‘+4 rule’. Whether you measure in inches or centimeters, get instant results tailored to UK sizing standards (from AA to HH cups). Over 250,000 women trust our calculator because it accounts for real-world quirks, such as tight bands at Boux Avenue, small cups at Primark, and everything in between. Say goodbye to strap slippage and painful wires—your comfort revolution starts here!

Why UK sizing is different / why measure accurately

The UK bra size chart follows a unique system that differs significantly from US, European, and Australian sizing conventions. UK sizing uses a sequential letter progression for cup sizes (A, B, C, D, DD, E, F, FF, G, etc.), while US sizing includes DDD instead of E and follows different increments. European sizing uses centimeter-based band measurements (like 70, 75, 80), making direct comparisons challenging without a proper bra size conversion chart UK reference.

These international variations mean a UK 32DD doesn’t equal a US 32DD—in fact, a UK 32DD converts to UK bra size to US as 32DD/E depending on the brand. Australian sizing closely mirrors UK conventions but with occasional variations in larger cup volumes. This is precisely why you need to find my UK bra size using measurements rather than assumptions based on other sizing systems.

Brand variation adds another layer of complexity. Even within the UK market, different manufacturers may fit slightly differently due to design philosophy, fabric stretch, and target demographics. A measurement guide tailored to UK standards ensures you start with an accurate baseline, which you can then adjust per brand if needed.

What you need before you start

Before using our bra size calculator UK tool, gather these simple items:

A soft measuring tape: Fabric or vinyl measuring tapes work best because they conform to your body’s contours without being rigid. Avoid metal tapes, which can’t flex properly and may give inaccurate readings.

A well-fitting unpadded bra or no bra: For the most accurate bust measurement UK results, take measurements while wearing a non-padded, unlined bra that doesn’t compress or enhance your natural shape. If you don’t own an unpadded bra, measuring without one works perfectly—just ensure you’re getting your true breast tissue measurement.

A mirror: Checking tape placement from multiple angles ensures the measuring tape stays level around your body, which is crucial for precision.

Notepad and pen: Recording your measurements helps you track changes over time and makes it easier to reference your numbers when shopping online or in-store.

Optimal timing matters too. Measure at home when you’re relaxed and your body isn’t affected by factors like water retention (which can fluctuate with your menstrual cycle) or post-exercise swelling.

Step-by-step measurements

Underbust / Band measurement — how to take it

Your band size forms the foundation of bra fit, providing 80% of breast support. Here’s how to measure bra size at home UK standards for the underbust:

Stand straight with arms relaxed at your sides. Position the measuring tape directly beneath your bust, where the back band of your bra would naturally sit. The tape should be parallel to the floor all the way around your torso—use your mirror to verify this.

Take a snug underbust measurement by keeping the tape comfortably firm against your skin without compressing your ribcage. You should be able to fit one finger underneath. Breathe normally and record this number in inches.

For UK sizing, round to the nearest even number. If you measure 29 inches, round to 30; if you measure 32.5 inches, round to 32. This rounding convention aligns with how UK retailers manufacture band sizes (28, 30, 32, 34, 36, etc.).

Some fitting methods also recommend a tight underbust measurement (pulled snug) to calculate support needs for larger cup volumes, though the snug measurement works for most body types.

Overbust / Bust measurement — how to take it

The overbust measurement determines your cup size when compared against your band measurement. For accurate results:

Stand in the same upright position. Wrap the measuring tape around the fullest part of your bust—typically across your nipples. The tape must remain level (parallel to the floor) and shouldn’t dig into your skin or hang loosely.

Take a standing bust measurement while breathing normally. The tape should skim your body with light tension—imagine holding a piece of paper against your chest without crushing it. Record this number in inches.

For the most accurate UK cup size chart matching, some people find taking additional angle measurements helpful, particularly if you have fuller or shallower breast shapes.

Optional: other measurements (leaning / lying)

If you’re full on top (more breast tissue above the nipple) or full on bottom (more tissue below), these supplementary measurements refine your fit:

Leaning bust: Bend at the waist to 90 degrees, allowing your breasts to hang perpendicular to your body. Measure around the fullest part—this often provides a more accurate cup volume assessment for fuller breasts.

Lying bust: Lie flat on your back and measure across the fullest part. This measurement helps if you have very soft breast tissue that behaves differently when standing.

Most people can skip these extra measurements and rely on standing measurements alone, but they’re valuable troubleshooting tools for persistent fit issues.

How the calculator works — the simple formula

Our best bra size calculator for UK sizing uses the standard UK calculation method that’s been refined over decades:

Step 1: Your rounded underbust measurement UK becomes your band size. For example, if you measured 32 inches snug, your band is 32.

Step 2: Subtract your band size from your bust measurement UK (standing). The difference in inches maps to cup letters:

• 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
• 8 inches = FF cup
• And so on…

Example calculation: If your underbust is 32 inches and your overbust is 37 inches, the difference is 5 inches. This gives you a 32DD UK bra size.

What does 32DD mean UK? It indicates a 32-inch band with a 5-inch difference between underbust and bust measurements, representing a specific cup volume relative to that band size.

The formula works seamlessly whether you measure in inches or centimeters—just ensure you use consistent units throughout and reference the appropriate size chart UK column.

UK size chart & conversions

Here’s a quick-reference UK bra size chart showing common sizes:

UK Band Sizes (inches): 28, 30, 32, 34, 36, 38, 40, 42, 44, 46

Cup Progression: A, B, C, D, DD, E, F, FF, G, GG, H, HH, J, JJ, K

Sample Size Chart:

UK Bra Size Chart (Band & Cup Guide)

Underbust (in)	Band Size	1″ Difference	2″ Difference	3″ Difference	4″ Difference	5″ Difference
28–29	28	A	B	C	D	DD
30–31	30	A	B	C	D	DD
32–33	32	A	B	C	D	DD
34–35	34	A	B	C	D	DD

UK Bra Size Chart (Inches & CM)

Difference	UK Cup	Inches	CM
1″	A	1″	2.5cm
2″	B	2″	5cm
3″	C	3″	7.5cm
4″	D	4″	10cm
5″	DD	5″	12.5cm
6″	E	6″	15cm
7″	F	7″	18cm
8″	FF	8″	20cm
9″	G	9″	23cm

UK Brand Sizing Guide

Brand	Band Fit	Cup Fit	Our Recommendation
M&S	Tight	Small	Size up in cups
Bravissimo	True	True	Trust calculator
Boux Avenue	Snug	Large	Size down in band
Primark	Loose	Small	Size down in both

UK to US Conversion:

• UK 32DD = US 32DD/E
• UK 32E = US 32DDD/F
• UK 32F = US 32G

Convert EU bra size to UK:

• EU 70 = UK 32
• EU 75 = UK 34
• EU 80 = UK 36
• (EU band = UK band + 10cm approximately)

UK to Australian: Generally identical, though some Australian brands use US sizing conventions.

This bra size conversion chart UK section helps you shop international brands with confidence.

Sister sizes — what they are & how to try them

Sister sizes UK are alternative sizes that offer the same cup volume but different band and cup letter combinations. This concept is invaluable when a bra fits well in the cups but feels too tight or loose in the band.

How to find sister size UK bra:

• Go up one band, down one cup: If 32DD feels tight in the band but perfect in the cup, try 34D
• Go down one band, up one cup: If 32DD feels loose in the band but the cups fit, try 30E

Both sister sizes maintain the same cup volume because cup size is relative to band size. A D cup on a 30 band contains the same breast tissue volume as a DD cup on a 32 band or a C cup on a 34 band.

Practical examples:

• 30DD ↔ 32D ↔ 34C
• 32E ↔ 34DD ↔ 36D
• 34FF ↔ 36F ↔ 38E

Sister sizing helps you fine-tune fit when shopping brands that run slightly large or small in the band, or when seeking different support level characteristics in similar cup volumes.

Common fit problems & troubleshooting

Even with accurate measurements, you might encounter these fit issues:

Gaping cups: Cups wrinkle or gap away from your breast tissue. This usually means the cup is too large, the style is wrong for your breast shape, or you need a different cup style (try going down one cup size or choosing a bra designed for your fullness pattern).

Cup overflow / Quadboob: Breast tissue spills over the top or sides of cups. Your cup is too small—go up one cup size. This is especially common in molded-cup bras that don’t accommodate full on top shapes.

Straps digging in: If straps leave painful marks, your band may be too loose (forcing straps to do all the support work). Try going down a band size or using the tighter hooks.

Back band riding up: The band should sit level around your torso. If it rides up your back, the band is too loose—go down a band size. A proper-fitting back band stays horizontal.

Underwire discomfort: Wires shouldn’t sit on breast tissue. If they do, you need a larger cup. Wires should trace the root of your breast tissue, sitting flat against your ribcage.

These issues often resolve with proper sizing, but sometimes they indicate you need a different style rather than a different size.

Tips for accurate results & choosing the right style

Best measuring practices:

1. Posture matters: Stand naturally straight—don’t arch your back or slouch, as this affects measurements.
2. Remeasure periodically: Weight fluctuations, hormonal changes, pregnancy, and aging all affect breast size. Remeasure every 6-12 months or after significant body changes.
3. Account for padding differences: Molded, padded bras fit differently than non padded bra size guide UK styles. Unlined bras conform to your natural shape, while padded styles may require sizing adjustments.
4. Consider your activity: Sports bra sizing UK often differs from everyday bras. Sports bras prioritize compression and encapsulation, so you might size differently based on impact level (low, medium, or high).
5. Professional fittings: If you’re between sizes or struggle with persistent fit problems, consider a professional fitting. Many UK retailers offer complimentary fitting services.
6. Plus size considerations: A plus size bra calculator UK uses the same method, though you may need to explore specialty brands that offer extended sizing like 40+ bands and G+ cups.
7. Petite sizing: Petite bra size UK needs are met by brands offering 28 and 30 bands. If you need small band bra sizes UK (30 band UK) or smaller, look for specialist retailers.
8. Specialty sizes: Looking for AAA bra size chart UK options? Very small cup volumes (AAA, AA) are less common but available through select brands specializing in smaller busts.

How to use the interactive UK Bra Size Calculator on this page

Using the Paradise Clothes UK bra size calculator is simple:

1. Enter your underbust measurement: Input your snug underbust measurement in the first field.
2. Toggle units: Select inches or centimeters using the unit switcher—the calculator converts automatically.
3. Enter your bust measurement: Input your standing bust measurement in the second field.
4. View results: The calculator instantly displays your UK band size and cup size.
5. Check sister sizes: The results include your two nearest sister sizes for alternative fitting options.
6. Review conversions: See your size converted to US, EU, and AU systems for international shopping.

The calculator stores no personal data and works entirely in your browser for privacy. Results update in real-time as you adjust measurements, making it easy to double-check or try different values.

For bra size calculator for nursing mothers UK needs, take measurements while wearing a comfortable nursing bra or no bra, as breast size fluctuates during breastfeeding.

Looking for bra size calculator for sports bras UK guidance? Use your standing measurements, then consult our sports bra support guide to match your impact level activity with appropriate compression levels.

FAQs — target common search queries

What if my underbust is an odd number?

Round to the nearest even number for UK sizing. If you measure 31 inches, round to 32. If you’re exactly between two sizes (like 31.5), try both the 30 and 32 band to see which feels more secure without being uncomfortable. How to measure bra size at home UK step by step guides consistently recommend this even-number rounding for best results.

Why do I wear different sizes in different brands?

Bra sizing isn’t fully standardized—brands use different patterns, fabrics with varying stretch, and design philosophies. A “full-coverage” style fits differently than a “balconette” style even in the same size. Additionally, UK sizing standards vary slightly between mainstream and specialty brands. Always check each brand’s specific size conversion chart and read reviews about whether they run large or small.

How often should I remeasure?

Remeasure every six months if your weight is stable, or immediately after significant changes like:

• Weight gain or loss (10+ pounds)
• Pregnancy or postpartum period
• Hormonal changes (starting/stopping birth control)
• Menopause
• After breast surgery

Many people find their size shifts slightly with seasonal weight fluctuations too. A quick remeasure takes only minutes and ensures optimal fit guide accuracy.

Can I measure without a tape?

In a pinch, use a non-stretch string or ribbon to measure, then lay it against a ruler. However, this method is less accurate than a proper measuring tape. For best results with the UK bra size calculator, invest in an inexpensive fabric measuring tape—they’re available at craft stores and online for under £2. Accurate measurements are the foundation of finding your perfect fit, so the right tools matter.

Conclusion

Finding your perfect fit doesn’t have to be complicated. With accurate measurements and our easy-to-use UK bra size calculator, you’re just minutes away from discovering bras that actually fit your body. Whether you need everyday comfort, sports bra support, or something special, Paradise Clothes is here to guide you through every step of your fitting journey.

Ready to find your size? Use our interactive calculator above to get your personalized UK bra size, sister sizes, and international conversions. Still have questions? Contact our fitting experts for a complimentary virtual consultation—we’re here to help you feel confident and comfortable in every bra you wear.

Start measuring today and experience the difference a properly fitted bra makes. Your body deserves the perfect fit, and Paradise Clothes is committed to helping you find it.