Sister sizes

Sister Size Finder

Enter a US bra size to see the same-cup-volume sizes in the active size range.

Starting size

How this works

Sister sizes move the band and cup in opposite directions to keep a similar cup volume while changing band fit.

US size

Same cup volume

34D

Snugger band

Looser band

Bras in your size

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Placeholder for a broad size range and return-friendly basics.

Placeholder for supportive everyday styles by band and cup.

Placeholder for wire-free and lounge options.

What is a sister size?

A sister size is a nearby band and cup combination that keeps roughly similar cup volume.

How does this MVP calculate sister sizes?

It moves one band step and one cup step in opposite directions: down a band and up a cup, or up a band and down a cup.

Can I use sister sizes for final buying decisions?

Use them as a starting point only. Fit depends on body shape, style, fabric, and brand.