Bra Cup Size Calculator UK: Easy and Accurate

How to Calculate Bra Cup Size in the UK?

Calculating your bra size in the UK is straightforward when you follow the right steps. You need two key measurements: your underbust and your bust. Start by measuring around your ribcage directly under your breasts. This gives you the band size. Then measure around the fullest part of your bust while wearing a non-padded bra.

The difference between these two measurements determines your cup size. For every inch of difference, you go up one cup size. For example, if there’s a 1-inch difference, you’re an A cup. A 2-inch difference means B cup, 3 inches is C cup, and so on. The UK sizing system is widely regarded as one of the most accurate because it doesn’t add extra inches to your measurements.

Here’s the key formula for UK bra sizing:

• Measure your underbust in inches and round to the nearest even number for your band size
• Measure your bust at the fullest point
• Subtract the band size from the bust measurement
• Use the difference to find your cup size (1″ = A, 2″ = B, 3″ = C, 4″ = D, 5″ = DD, 6″ = E, etc.)

Which Cup Size is Bigger: A or B or C?

The cup size progression in bras follows alphabetical order, which makes it easy to remember. Cup size A is the smallest, followed by B, then C. Each letter represents an additional inch in the difference between your underbust and bust measurements.

Here’s a simple breakdown of cup sizes:

Remember that cup size isn’t absolute. A 32C has a smaller cup volume than a 36C because the cup size scales with the band size. This concept is called sister sizing, which we’ll explore more below.

What is the 3 Bra Rule?

The 3 bra rule is a practical guideline for maintaining your lingerie collection. Fashion experts and lingerie specialists recommend owning at least three bras in rotation. This ensures each bra gets proper rest between wears, extending its lifespan significantly.

Why three bras? When you wear a bra, the elastic stretches throughout the day. It needs at least 24 hours to return to its original shape. By rotating between three bras, each one gets two days of rest. This simple practice can double or even triple the life of your bras.

Here’s how to implement the 3 bra rule effectively:

• Have one bra in the wash, one being worn, and one resting
• Wash your bras after every 2-3 wears (unless you’ve been sweating heavily)
• Hand wash or use a delicate cycle with a lingerie bag
• Always air dry your bras – never use a tumble dryer as heat damages elastic
• Store bras flat or hang them to maintain their shape

Many women find that having more than three bras is ideal. Consider having different styles for different occasions, such as sports bras for exercise, seamless t-shirt bras for everyday wear, and prettier styles for special occasions.

What is the 2 Finger Rule for Bras?

The 2 finger rule is a quick fitting test to check if your bra band is the right tightness. When wearing your bra on the loosest hook, you should be able to slide two fingers under the band comfortably. If you can fit more than two fingers, the band is too loose. If you can’t fit two fingers, it’s too tight.

This rule works because your bra band provides most of the support, not the shoulder straps. A properly fitted band should feel snug but not restrictive. You should be able to breathe normally and move comfortably without the band riding up your back.

Here are additional fitting checks beyond the 2 finger rule:

• The band should sit level around your body, parallel to the floor
• The center gore (the piece between cups) should lie flat against your sternum
• Your breasts should fill the cups completely without spillage or gaping
• The underwire should encompass all breast tissue without digging in
• Shoulder straps should stay in place without digging into your shoulders
• You should fasten your new bra on the loosest hook, allowing you to tighten it as the bra stretches over time

Measuring Your Bra Size: Your Options

You have several options when it comes to measuring your bra size. Each method has its advantages depending on your situation and preferences.

At-Home Measurement

This is the most convenient option and works well for most women. You’ll need a soft measuring tape and a non-padded bra. Take your measurements in front of a mirror to ensure the tape is level. Our calculator above uses this method and provides instant results with international conversions.

Professional Fitting

Many lingerie shops and department stores offer free professional fittings. A trained fitter can help you navigate tricky sizing situations and recommend styles that suit your breast shape. This is particularly helpful if you’re between sizes or have asymmetrical breasts.

Virtual Fitting Services

Some online retailers now offer AI-powered virtual fitting tools. These use your smartphone camera to analyze your measurements and recommend sizes. While convenient, these tools work best as a starting point rather than a definitive answer.

Sister Sizing Method

If you know your current size but want to adjust the fit, sister sizing helps you find equivalent sizes. Going up a band size and down a cup size (or vice versa) maintains the same cup volume while changing the band fit. For example, 34C and 36B are sister sizes.

When Might I Need a New Bra?

Knowing when to replace your bras is crucial for maintaining proper support and comfort. Most bras last between 6 to 12 months with regular wear, but several factors can shorten or extend this timeframe.

Here are clear signs that indicate you need a new bra:

• The band rides up your back, even on the tightest hook
• The elastic has lost its stretch and feels loose
• The underwire pokes through the fabric or has become misshapen
• The cups have lost their shape or show permanent creasing
• Straps constantly slip off your shoulders despite adjustment
• The center gore no longer lies flat against your chest
• You experience shoulder or back pain when wearing the bra
• The fabric has become thin, discolored, or shows visible wear

Beyond wear and tear, certain life changes require remeasuring and purchasing new bras. Weight fluctuations of more than 10 pounds, pregnancy, breastfeeding, hormonal changes, and menopause can all affect your bra size. It’s recommended to measure yourself every 6 to 12 months, even if you haven’t noticed obvious changes.

Investing in quality bras and caring for them properly extends their lifespan. However, don’t hold onto bras that no longer fit properly. Wearing an ill-fitting bra can lead to discomfort, poor posture, and inadequate breast support. Your comfort and health are worth the investment in new, properly fitted bras.