US to EU conversion

40A in European Bra Size

Convert 40A from US sizing to European sizing, with the full international table, nearby sister sizes, and fit checks in one place.

Instant answer

40A (US) =

90A EU

In this sizing table, 40A in US sizing converts to 90A in European sizing.

Sizing varies by brand

A conversion gives you the closest label in another sizing system, but brands can grade cups, wires, and bands differently. Use the converted size as a starting point, then check the retailer's chart and the fit of the actual bra.

Before you buy in European sizing

Use 90A as the translated label, not as a fit guarantee.
Check the retailer's size chart because some brands grade bands and cups differently.
If the cup volume feels close but the band changes, compare sister sizes before switching cup letters.
When possible, check return rules before buying across sizing systems.

Full conversion table for 40A

40A bra size conversion across US, UK, EU, French, and Australian sizing.
US	UK	EU	FR	AU
40A	40A	90A	105A	18A

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

Sizes near 40A in European sizing

If 40A is close but not right, these are the neighbouring US sizes and what each one becomes in European sizing. Band neighbours change the fit around the ribcage; cup neighbours change volume.

US sizes adjacent to 40A and their European equivalents.
US size	EU size	How it differs
38A	85A	One band step snugger, same cup letter.
40B	90B	One cup step up, same band.

What this conversion means

Bra size conversions are label translations, not fit guarantees. For 40A to European, this dataset shows 90A; fabric, wire shape, and brand grading can still make two bras with the same label feel different.

Sister sizes for 40A

Sister sizes: 38B can be worth checking when the cup volume feels close but the band needs a different feel.

What measurements make a 40A?

The useful way to read 40A is to separate the band from the cup step. In the current calculator formula, the closest starting range is about 39-41 inches (99-104 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.

Is 40A big or small?

Whether 40A feels small, average, or full depends on the body and on the brand. In this size set, the US equivalent uses a fuller band and a lower 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 40A 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 40A differs between brands

40A can shift in feel from one retailer to another because brands grade bands and cups in their own way. 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 40A

40A is easiest to compare when you try shapes that show both cup volume and band tension clearly. 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.

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Soft Cup Edit

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FAQ

Is 40A in the US the same as European sizing?

The closest European label here is 90A. It is a conversion guide, so retailer charts and try-on fit still matter.

What is 40A in French sizing?

In this same table, 40A converts to 105A (FR). That helps when a retailer shows a French chart instead of a European one.

How do I know if 40A fits?

Start with the band: it should feel firm and even around your ribcage. Then check cup containment and comfort across the style you are actually trying on.

What sister sizes work with 40A?

38B are the closest sister-size options for 40A 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?

Countries and brands do not all use the same band labels or cup-letter sequence. A conversion translates the closest standard label, but the final fit still depends on the specific bra.

What measurements usually make 40A?

The current calculator formula points to about 39-41 inches underbust and 40.5-41.5 inches bust, or roughly 99-104 cm and 103-105 cm. Treat that as a starting range and then check the real fit.