US to EU conversion

40DD in European Bra Size

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

Instant answer

40DD (US) =

90E EU

In this sizing table, 40DD in US sizing converts to 90E 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 90E 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 40DD

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

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

Sizes near 40DD in European sizing

If 40DD 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 40DD and their European equivalents.
US size	EU size	How it differs
38DD	85E	One band step snugger, same cup letter.
40D	90D	One cup step down, same band.
40DDD	90F	One cup step up, same band.

What this conversion means

A US 40DD means a 40 band with a DD cup step. The European equivalent in this table is 90E, which keeps the same general fit target but uses European labeling. If the cup feels close and the band feels off, sister sizing is usually the next thing to try.

Sister sizes for 40DD

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

What measurements make a 40DD?

40DD starts with the underbust, then adds cup depth from the bust measurement. In the current calculator formula, the closest starting range is about 39-41 inches (99-104 cm) under the bust and about 44.5-45.5 inches (113-116 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 40DD big or small?

The label 40DD can look more dramatic than it fits, especially across systems. In this size set, the US equivalent uses a fuller band and a fuller 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 40DD 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 40DD differs between brands

Brand sizing matters for 40DD because cup depth, wire width, and band stretch are design choices. 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 40DD

A good shopping path for 40DD starts with everyday support, then moves into outfit-specific shapes. 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

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Comfort Band Co.

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Soft Cup Edit

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FAQ

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

Not exactly. 40DD is the US label, and this table converts it to 90E in European sizing, though some brands publish their own charts.

What is 40DD in Australian sizing?

In this same table, 40DD converts to 18DD (AU). That helps when a retailer shows a Australian chart instead of a European one.

How do I know if 40DD fits?

Check that the band stays level, the cups do not spill or gap, and the center gore sits close if the bra has wires. If the cup feels right but the band feels wrong, try a sister size.

What sister sizes work with 40DD?

38DDD are the closest sister-size options for 40DD 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 40DD?

The current calculator formula points to about 39-41 inches underbust and 44.5-45.5 inches bust, or roughly 99-104 cm and 113-116 cm. Treat that as a starting range and then check the real fit.