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Plus Size Bra Calculator

The formula doesn't change at larger sizes — but which features actually deliver support does. Enter your measurements to get your size, plus what's worth prioritizing above a 38 band or D cup.

Enter both measurements to continue.

Your size
40D
band 40 · cup index 4

A schematic fit diagram, scaled to your cup size.

Same formula, wider range

Band and cup are still calculated exactly the same way — round your underbust for the band, then read the bust-to-band gap for the cup letter. The scale simply keeps climbing past where many everyday charts stop showing examples.

band = round(underbust, in)
cup difference = round(bust, in) − band

Where things genuinely change is construction: wider bands, wider straps, extra hooks and reinforced wiring all start to matter more as both numbers climb, even though the underlying maths never does.

What to prioritize

Features worth checking above 38/D

Straps

Wider, cushioned straps

More surface area on the shoulder spreads weight and reduces digging-in as cup volume increases.

Band

Extra hook rows

A third or fourth hook row gives more range to fine-tune the band as elastic relaxes over time.

Wire

Reinforced or wider wire

A wire built for the size range, not just stretched from a smaller pattern, holds its shape better under more weight.

Fabric

Structured, not just stretchy

Some structure in the cup and band helps distribute support rather than relying on stretch alone.

Questions

Plus size FAQs

No — the same band-plus-cup-difference formula applies at every size. What changes at larger sizes is which construction features actually deliver on that size.

Wider straps spread weight across more surface area on the shoulder, reducing the digging-in sensation that narrow straps cause as cup size increases.

Many plus-size specific styles add a third or fourth hook row for a wider range of adjustment, which is worth checking for compared to standard two-hook bands.

No — band and cup are sized independently. A snug, level band matters at every cup size, not more or less so at larger ones.

Mainstream retailers often carry a narrower size run than specialist plus-size brands, so trying the sister sizes around your result can widen your options.

The same accurate formula, every size.

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