Bra Size Calculator
Use this bra size calculator to estimate your correct bra size using bust and underbust measurements. Enter your measurements below to find your band size and cup size instantly.
Measure around your ribcage just under the bust
Measure around the fullest part of your bust
Your Estimated Bra Size
Sister Sizes
How the Bra Size Calculator Works
A bra size calculator estimates bra size by comparing the bust measurement with the underbust measurement. The underbust determines the band size while the difference between bust and band determines the cup size.
How to Measure Correctly
- Wear a non padded bra
- Use a flexible measuring tape
- Measure the ribcage under the bust
- Measure the fullest part of the bust
- Keep the tape parallel to the floor
Best Bra Fabrics
- Cotton – breathable everyday comfort
- Microfiber – lightweight and smooth
- Modal – soft on sensitive skin
- Lace blends – stylish stretch support
Bra Size Calculator FAQs
How accurate is a bra size calculator?
A bra size calculator provides a starting estimate based on bust and underbust measurements.
Different brands and bra styles may fit slightly differently.
How often should you measure bra size?
Experts recommend measuring your bra size every 6–12 months or whenever body shape changes.
What are sister sizes in bras?
Sister sizes are bra sizes with the same cup volume but different band sizes such as 34C, 32D, and 36B.
Why does my bra feel uncomfortable?
If straps fall, cups overflow, or the band rides up your back, your bra size may not be correct.