Bra Size Calculator UK

Enter your measurements in centimetres to find your UK bra size.

How to Measure Your Bra Size

To find your bra size in UK sizing, you need two key measurements:

  • Underbust: Measure firmly around your ribcage just below your breasts. This determines your band size.
  • Bust: Measure around the fullest part of your breasts with a relaxed posture.

Both measurements should be taken in centimetres for the most accurate conversion.

UK Bra Sizes

The UK bra size consists of a number and a letter. The number is your band size, which relates to the underbust measurement, and the letter indicates the cup size, which corresponds to the difference between your bust and underbust measurements.

Band sizes are rounded to the nearest 5 cm interval to match UK standards. Cup sizes increase with each 2.5 cm increment difference:

  • Difference < 12.5 cm = AA
  • 12.5 – 14.9 cm = A
  • 15 – 17.4 cm = B
  • 17.5 – 19.9 cm = C
  • 20 – 22.4 cm = D
  • 22.5 – 24.9 cm = DD / E
  • 25 – 27.4 cm = DDD / F

If your size falls outside this range, consider consulting a professional fitter for a tailored recommendation.

Frequently Asked Questions

Why is my band size larger than my underbust measurement?

Band sizes are rounded to the nearest 5 cm (e.g., 70, 75, 80). Your actual underbust measurement may be slightly smaller, but bra bands need some allowance for comfort and stretch.

Can bra sizes vary between brands?

Yes, sizes might vary slightly due to different cuttings and materials. Always try on bras before purchasing if possible.

How often should I measure my bra size?

It’s recommended to measure every 6-12 months, as body changes can affect the fit.

What if I fall between two cup sizes?

Try the larger cup size for comfort or consult a fitter for custom advice.

Using Your Bra Size

Now that you know your UK bra size, use it to shop more confidently and select bras that offer proper support and comfort. A well-fitting bra can improve posture, reduce discomfort, and boost confidence.

If uncomfortable, consider trying sister sizes (one band size up and one cup size down, or vice versa) to find the best fit.

References

Bradley, K.M. “Bra Fitting and Female Anatomy.” Journal of Apparel Science, 2019.

UK Charity Guide “Measuring Your Bra Size.” Breast Cancer Care UK, 2021.

Smith, J. “Understanding Bra Sizes: A Practical Guide.” British Journal of Clothing Technology, 2020.