BraFit

Bra Size Calculator (US)

US sizing — band even to nearest 2, cup from the bust minus band.

Band measurement (in)

Bust measurement (in)

Band size (US)

US sizing. UK/EU sizes differ.

Cup size (US): D
Cup difference (in): 4

What you entered

Band measurement (in): 32Bust measurement (in): 36

1
Round band measurement to the nearest even number
2 × round(32 ÷ 2)= 32 in
2
Cup difference (bust − band)
36 − 32= 4.0 in
3
Map the difference to a cup letter
round(4.0) → step 4= D

Result

Band size (US): 32

A 32 in band and 36 in bust works out to a US 32D — try on both this and adjacent sizes, since fit varies by brand.

Cup size from band and bust measurements

Cup size comes from the difference between the bust and band measurements: roughly one inch of difference per cup letter.

Band	Bust	Difference	Size
32 in	34 in	2 in	32B
32 in	35 in	3 in	32C
34 in	37 in	3 in	34C
34 in	38 in	4 in	34D
36 in	40 in	4 in	36D
38 in	43 in	5 in	38DD

Sizing is not standardised between brands or between countries, so treat this as a starting point for trying sizes on rather than a fixed answer.

Two separate measurements, one size

Band size comes from your ribcage measurement (rounded to the nearest even number), while cup size comes from the difference between bust and band — each inch of difference steps up one cup letter.

Why proper fit matters

An estimated size from a measuring tape is a solid starting point, but brands vary enough in cut that trying a size on is still the most reliable way to confirm fit.

Frequently asked questions

How do I measure my bra size at home?

You need two measurements in inches: (1) Band — wrap a tape snugly around your ribcage just under the bust. Round to the nearest even number. (2) Bust — measure around the fullest part of the bust, tape level and not tight. Cup = bust − band: 1" = A, 2" = B, 3" = C, 4" = D, 5" = DD.

What is a sister size in bras?

Sister sizes share the same cup volume but differ in band size. Going up a band size → go down a cup letter (and vice versa). 34C, 36B, and 32D are all sister sizes with the same cup volume. This is useful when your exact size isn't available — try a sister size for a comparable fit.

Why do bra sizes vary between brands?

There's no universal standard for bra sizing. Brands use different fit models, cup shapes, and even measurement rounding methods. A 34C in one brand may fit like a 36B in another. Use calculator results as a starting point, then try on — especially when switching brands.