Bra Size Calculator & Chart
This Bra Size Calculator & Chart helps you easily measure your bra size at home. Follow our guide to find your perfect fit.
Tips Before You Get Started
- Wear a non-padded, unlined bra Padded or push-up styles add volume that throws off your numbers. A soft, unlined bra gives you the most accurate baseline.
- Grab a soft measuring tape A flexible fabric or plastic tape is essential. No tape? A piece of string and a ruler works just as well.
- Stand straight with your arms relaxed Your posture affects your measurements more than you'd think. Stand naturally — no holding your breath, no slouching.
- Check the tape is level all the way around Use a mirror, or ask someone to help. Even a slight dip at the back can shift your measurement by a full size.
How to Use The Size Chart
Use this sister size chart as a general guide to understand how bra sizes can relate to one another. Sizes listed in the same row usually share a similar cup volume, even though the band size is different. Keep in mind that bra fit can vary by style, fabric, stretch, wire construction, and brand sizing. Your calculated size is a helpful starting point, but the best fit should still feel comfortable through the band, cups, straps, and center front.
For example, if you usually wear a 34C and the cups feel right but the band feels too tight, your sister size may be 36B. If the band feels too loose, you may try 32D instead. A 36D has a similar cup volume to 34DD/E and 38C, while a 40DD/E is close in cup volume to 38DDD/F and 42D. Sister sizing works best when the cup volume feels right, but the band needs a better fit.
How to Measure Your Bra Size Accurately
Before using our bra sizing chart, grab a soft measuring tape and take two quick measurements—this is the key step in how to measure bra size accurately. These measurements help you find your ideal band and cup fit so you can choose a bra that feels truly comfortable and supportive.
How to Use The Size Chart
Use this sister size chart as a general guide to understand how bra sizes can relate to one another. Sizes listed in the same row usually share a similar cup volume, even though the band size is different. Keep in mind that bra fit can vary by style, fabric, stretch, wire construction, and brand sizing. Your calculated size is a helpful starting point, but the best fit should still feel comfortable through the band, cups, straps, and center front.
For example, if you usually wear a 34C and the cups feel right but the band feels too tight, your sister size may be 36B. If the band feels too loose, you may try 32D instead. A 36D has a similar cup volume to 34DD/E and 38C, while a 40DD/E is close in cup volume to 38DDD/F and 42D. Sister sizing works best when the cup volume feels right, but the band needs a better fit.
How to Measure Your Bra Size Accurately
Before using our bra sizing chart, grab a soft measuring tape and take two quick measurements—this is the key step in how to measure bra size accurately. These measurements help you find your ideal band and cup fit so you can choose a bra that feels truly comfortable and supportive.
1. Measure Your Underbust (Band Size)
Wrap a soft measuring tape around your ribcage, right under your bust where your bra band normally sits. Keep the tape level and snug, but not tight. Then match your underbust measurement to the band chart to find your band size.