How do I measure my bra size at home?

You need two measurements: underbust and bust. For underbust, wrap a measuring tape snugly around your ribcage just below your breasts. For bust, measure around the fullest part of your bust while wearing a non-padded bra. Enter both measurements in our calculator above.

What is a sister size in bras?

Sister sizes are bra sizes that share the same cup volume but with different band sizes. For example, 34C, 32D, and 36B are all sister sizes. If your band feels too tight, try the sister size one band up. If it's too loose, try one band down.

How do I convert US bra sizes to UK?

US and UK band sizes are the same (32, 34, 36, etc.). Cup sizes differ after D: US DD = UK DD, US DDD = UK E, US G = UK F. Our calculator converts automatically between all systems.

How often should I measure my bra size?

It's recommended to measure your bra size every 6-12 months, as your size can change due to weight fluctuations, hormonal changes, pregnancy, or aging. If your bra feels uncomfortable or doesn't fit well, it's time to remeasure.

What if I am between two bra sizes?

If you are between band sizes, round down to the nearest even number for a snugger fit. If between cup sizes, size up for comfort. You can also try sister sizes — a smaller band with one cup size up, or a larger band with one cup size down.

Bra Size Calculator

Find your bra size in US, UK, EU, and AU

Underbust measurement

Bust measurement

Measure snugly around your ribcage (underbust) and at the fullest part of your bust.

Your measurements are calculated locally and never sent to a server.

How to Measure Your Bra Size

Illustration showing where to measure bust and underbust for bra sizing

Band (underbust) Bust (fullest point)

Measure your bust

Wrap a tape around the fullest part of your bust. Keep it level and not too tight.

Measure your underbust

Wrap the tape snugly around your ribcage, just below your breasts. Keep it level.

Enter your measurements

Use our calculator to get your size in US, UK, EU, and AU systems with sister sizes.

Bra Size Systems Explained

US Bra Sizes

Band sizes in even numbers (28-44) with cup sizes A through I. The most common sizes in the US are 34B, 34C, and 36C. Sizes beyond DDD use letter progression: G, H, I.

UK Bra Sizes

Same band numbers as US. Cup sizes differ after D: UK uses DD, E, F, FF, G, GG, H progression. UK sizing is considered more standardized than US.

EU Bra Sizes

Band sizes use centimeters in increments of 5 (65, 70, 75, 80, 85, 90). US 32 = EU 70, US 34 = EU 75, US 36 = EU 80. Cup letters follow the same A-F progression.

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