BraSizeCalc Tip

Bra size calculator

Measure snugly around your ribcage just under your bust (underbust) and loosely around the fullest part of your bust. BraSizeCalc rounds the underbust to the nearest even number for the band, then counts one cup letter for every inch the bust is bigger than the band: 1 inch is an A, 2 a B, 3 a C, 4 a D.

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    Cup letters split after D: UK sizing goes DD, E, F, FF and US sizing goes DD, DDD, G, H, so the calculator shows both, plus EU and other systems.

    How the bra size calculator works

    BraSizeCalc uses the inch-based method most US and UK brands publish. The band is your underbust rounded to the nearest even inch (modern method), or, if you choose the traditional method, rounded to the nearest inch with 4 added for an even number and 5 for an odd one. The cup is the bust measurement minus the band, rounded to the nearest inch, with one letter per inch. Centimetre measurements are divided by 2.54 first. EU bands are 70 for a 32 and go up 5 for each band size; French bands are EU + 15; Australian bands are the inch band minus 22.

    Cup letters by bust minus band

    DifferenceUSUKEU
    under ½ inAAAAAA
    1 inAAA
    2 inBBB
    3 inCCC
    4 inDDD
    5 inDDDDE
    6 inDDDEF
    7 inGFG
    8 inHFFH
    9 inIGI
    10 inJGGJ
    11 inKHK
    12 inLHHL
    13 inMJM
    14 inNJJN
    15 inOKO

    Band sizes

    Underbust (in)Band US/UKEUFRAU
    27–292860756
    29–313065808
    31–3332708510
    33–3534759012
    35–3736809514
    37–39388510016
    39–41409010518
    41–43429511020
    43–454410011522

    Brands cut differently, so treat the result as a starting size and check the fit: the band should be level and firm, the centre gore should sit flat and the cups should not gap or spill. Sizes past DD vary most between brands.

    Frequently asked questions

    How do I calculate my bra size?

    Round your underbust to the nearest even inch for the band. Subtract the band from your bust measurement: each inch is one cup size (1 = A, 2 = B, 3 = C, 4 = D, 5 = DD).

    What is the difference between US and UK cup sizes?

    They match up to DD. After that UK goes E, F, FF, G, GG and US goes DDD (F), G, H, I, J.

    Should I measure with a bra on?

    Wear a non-padded bra that fits reasonably well, or measure braless while leaning slightly forward for the bust measurement.

    Is BraSizeCalc free?

    Yes, with no sign-up or ads.

    Are my measurements saved or sent anywhere?

    They are saved in this browser only and never leave your device.

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