British Bra Size Calculator with Measurement Chart

The British bra sizing system uses inches to determine both band and cup sizes. The system is straightforward and based on two key measurements that work together to provide proper support and comfort.

The band size represents the measurement around your ribcage under your breasts, rounded to the nearest even number (28, 30, 32, 34, 36, 38, 40, 42, 44, etc.). This provides the primary support for your breasts, accounting for approximately 80% of the bra's support function.

The cup size is determined by the difference between your overbust and underbust measurements. In the UK system, each inch of difference corresponds to one cup size progression. The British cup sequence follows: AA, A, B, C, D, DD, E, F, FF, G, GG, H, HH, J, JJ, K, KK, L.

Understanding sister sizes allows flexibility when a bra fits well in the cups but not in the band. For example, if you normally wear a 34C but find the band too tight, you can try a 36B (larger band, smaller cup letter). Conversely, if the band feels loose, try a 32D (smaller band, larger cup letter).

• Band Support: The band should provide 80% of the bra's support. It should sit horizontally across your back, remain firm without digging in, and stay in place without riding up during movement.
• Cup Coverage: Your breasts should fill the cups completely without spillage over the top or sides. The center gore (front panel) should lie flat against your sternum between your breasts.
• Strap Adjustment: Straps should stay on your shoulders without slipping or digging in. You should be able to slide two fingers underneath comfortably. Straps provide support but should not bear the primary weight.
• Wire Position: Underwires should rest against your ribcage in the crease beneath your breasts, not on breast tissue. The wires should follow your breast root without poking or pressing uncomfortably.
• Hook Position: Choose a bra that fits comfortably on the loosest hooks. As the bra stretches with wear, you can tighten to the middle and tightest hooks to extend its lifespan.
• Movement Test: Raise your arms, bend forward, and move around while trying on bras. A well-fitted bra stays in place without shifting, and your breasts remain securely in the cups during normal movement.
• Regular Remeasurement: Measure yourself every six months or after significant weight changes, pregnancy, or hormonal fluctuations. Breast size can change throughout your menstrual cycle and over time.

If the band rides up your back, the band size is too large. Try going down a band size and up a cup size to maintain the same cup volume. The band should remain horizontal and parallel to the ground.

Breast tissue spilling over the top, sides, or under the arms indicates cups that are too small. Increase your cup size by one or two letters. Ensure you're scooping all breast tissue into the cups when putting on your bra.

Empty space or wrinkling in the cups means the cup size is too large. Try decreasing the cup size, or the bra style may not suit your breast shape. Different styles work better for different breast shapes.

Painful strap indentations suggest the band isn't providing enough support and the straps are compensating. Try a smaller band size or adjust the straps to be less tight. Properly fitted straps should support, not strain.