FR to US conversion

FR 100C in US Bra Size

Convert 100C from French sizing to US sizing, with the full international table, sister sizes, and practical fit checks in one place.

Instant answer

100C (FR) =

38C US

In this sizing table, 100C in French sizing converts to 38C in US sizing.

Full conversion table for 100C (US 38C)

38C bra size conversion across US, UK, EU, French, and Australian sizing.
US	UK	EU	FR	AU
38C	38C	85C	100C	16C

Bra sizing varies between brands. Use this as an accurate starting point and check the fit.

What this conversion means

Reverse conversions are useful when a tag, retailer, or size chart starts outside the US system. In this table, FR 100C converts to US 38C, then the adjacent links help you compare nearby options.

Sister sizes for the US equivalent (38C)

Sister sizes: 36D and 40B can be worth checking when the cup volume feels close but the band needs a different feel.

What measurements make a 100C?

For 100C, the band number gives the ribcage anchor and the cup describes the bust difference. In the current calculator formula, the closest starting range is about 37-39 inches (94-99 cm) under the bust and about 40.5-41.5 inches (103-105 cm) around the fullest part of the bust. The band comes from the underbust rounding, while the cup step comes from the difference between bust and band. This page uses 38C as the US equivalent for those measurement notes.

Is 100C big or small?

100C sits in context only when the number and letter are read as a pair. In this size set, the US equivalent uses a fuller band and a middle cup step. Cup letters are relative to the band, so a D on one band is not the same volume as a D on every other band. The most useful question is whether the band stays level and the cups hold smoothly, not whether the label sounds large or small.

If 100C doesn't fit right

Band rides up: The band may be too loose or stretched out; try a snugger band or compare the snugger sister size.

Cups gape: The cup may be too roomy, too deep, or pulled away by a loose band; check the band before changing cup volume.

Cups spill: The cup volume may be too small or the cup shape may be too closed; try one cup step up before changing the band.

Straps dig in: The straps may be compensating for a band that is not supporting enough; reset the band fit before tightening straps.

How 100C differs between brands

A conversion points you to a label, but a brand chart tells you how that maker expects 100C to fit. A firmer elastic can make the same band feel smaller, and a shallow or narrow cup can make the same cup letter feel different. Check the retailer chart, read fit notes when available, and compare the label against the brand and region sizing guide before treating the conversion as final.

Shopping for 100C

For 100C, practical shopping is less about one perfect style and more about reading the fit quickly. If the cup is in a lower or middle step, lightly lined T-shirt styles can make gaps easy to spot. Fuller cup steps often benefit from styles with steadier side support, deeper cups, or a balconette shape depending on breast shape. For special outfits, compare the fit needs in the outfit guides before choosing a strapless, plunge, or backless option.

Bras in your size

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Everyday Fit Store

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

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Comfort Band Co.

Placeholder for supportive everyday styles by band and cup.

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Soft Cup Edit

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FAQ

Is 100C the same as 38C in the US?

In this dataset, 100C (FR) converts to 38C in US sizing. Some brands publish their own charts, so use this as the closest standard label and still check the real fit.

What is 100C in European sizing?

100C (FR) matches the same base record as 85C (EU). The full table on this page shows each supported label side by side.

How do I check the fit of 38C?

Check that the band stays level, the cups sit smoothly without spilling or gapping, and the straps are not doing all the support work. The converted US size is a starting point, not a guarantee.

What sister sizes work with 38C?

36D and 40B are the closest sister-size options for 38C in this dataset. Try a sister size when cup volume feels close but the band needs to feel snugger or looser.

Why do bra sizes differ between countries?

Bra labels are written differently across US, UK, EU, French, and Australian systems. Cup letters can also diverge after D, so a converted label is a starting point rather than a promise of identical fit.

What measurements usually make 100C?

100C maps to US 38C here. The current calculator formula points to about 37-39 inches underbust and 40.5-41.5 inches bust, or roughly 94-99 cm and 103-105 cm. Treat that as a starting range and then check the real fit.