Independent fit tool

Six measurements · Eight sizing systems · Private in-browser calculation

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Compare band and cup separately

Bra Size Comparison Calculator: Which Bra Size Is Bigger?

Compare any two bra sizes to separate band length from approximate cup capacity and see whether the labels are sister sizes.

Band and cup capacity34DD vs 36D example

Compare two bra sizes side by side

First bra size
Second bra size
Sister-size match

34DD UK and 36D UK have similar cup volume

Band

36D UK is 1 standard band step roomier.

Cup volume

These are sister sizes: the band changes while approximate cup capacity stays similar.

Cup-volume steps are approximate and compare capacity, not cup shape, wire width or stretch. Brand charts remain the final reference. UK sizing uses double letters such as FF, GG and HH after F.

How to compare two bra sizes correctly

A bra size combines two variables. The number describes band length, while the cup letter describes a volume step relative to that band. This calculator normalizes both labels to the same band and cup progression, then reports the differences separately.

Is a 34DD bigger than a 36D bra?

A 36D has a band one standard step larger than a 34DD, but the two sizes have approximately the same cup volume. That makes 34DD and 36D sister sizes rather than one size being bigger in every way.

Why the same cup letter can hold different volumes

Cup letters are not fixed volumes. A D cup on a 38 band is larger than a D cup on a 34 band. Moving up one band while keeping the same cup letter increases both band length and approximate cup capacity.

What a bra size comparison cannot predict

Equal cup capacity does not mean identical fit. Cup depth, height, wire width, fabric stretch and brand grading can all differ. Use this result to choose sizes to try, then check the specific brand chart and evaluate the bra on your body.