Find your bra size
Take two measurements with a soft tape, in your usual bra with no padding, and this will estimate a starting size. Sister sizing varies by brand, so treat it as a fitting-room starting point.
Band measurement
Wrap the tape snugly around your ribcage, directly under the bust. Keep it level and parallel to the floor. Round to the nearest whole inch or cm.
Bust measurement
Wrap the tape around the fullest part of your bust, keeping it level and relaxed, not pulled tight. Breathe normally while you read the number.
Your measurements
Your estimated size will appear here.
Estimated size
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Before you buy
• Sizes aren't standardized across brands — treat this as a starting point, not a final answer.
• If the number falls between two bands, most people fit better in the smaller, firmer band.
• A band that rides up in back is usually too big; straps digging in usually mean the band, not the strap, needs adjusting.
• Cups should fully contain the bust with no spilling over the top or gapping at the edges.
This calculator uses a common estimation formula and is meant for general guidance only. Actual fit varies by brand, style, and body shape — an in-person or virtual fitting will always be more accurate.
