How Big Is a 40B Bra?

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Bra shopping and fitting can be difficult because every brand is different, and many people don’t understand bra sizes and their meaning. With the various international sizing systems and the sizing differences between brands, it can be challenging to determine what size you require. Do you think you’re a 40B? Let’s find out how big 40B is.

How Big Is a 40B Bra?

If you wear a bra size 40B, your bust measurement is 40 to 41inches, and your underbust measurement is 35 to 36 inches.

Graphic image of a woman wearing a pink tank top and black shorts that explains that a 40B bra size has a bust size range of 41-42 inches and a band size of 39-40 inches

While 40B bras are among the most popular sizes, there are several factors to consider when determining the best B-Cup bra for your breast shape.

Your sister size is 38C and 42A.

B-cup bra sizes will give you a comfortable and stunning fit in everything from daily bras to strapless bras.

At the same time, there are many 40B bra styles to choose from. Among the most prominent have adjustable straps, a durable hook-and-eye closure, and foam cups that compliment your curves.

There are also convertible bras for 40B cups that can be worn in various ways. There are also bralettes in 40B cups for support and sports bras for whatever moves you make either when exercising or doing yoga.

If you have a larger frame with small breasts, like a 40B, take a look at our #1 recommended push up bra: the Maidenform Demi Push Up Bra. Super comfortable, this specific bra features Wonderbra technology to give you a natural looking lift!

Which Bra Should You Wear if Your Cup Size Is 40B?

Women with a 40B-cup bust have it easy when it comes to bra selection. As a result, they can look good in any bra. Choose wisely, however, because each type of bra has a different effect on the appearance of the cleavage. Comfort also differs from one style to the next.

A nude push-up underwired bra with adjustable straps and ribbon at the center is placed on blue background

Related Questions

Is the C Cup Larger Than the B Cup?

C and B cups appear differently on different people depending on their ribcage and bust measurements. B cup size is right next to A cup size, thus slightly larger. What exactly is this? Women sometimes wish to have larger breasts, so they try to wear C-cup bras, and the opposite is true.

Should I Increase My Cup Size or Band Size?

Band size influences proper cup fit—the cup size changes as the band size changes. It would be best if you went up one cup size for every band size.

What’s the Difference Between Cup Sizes B and C?

Your bust line measurement will be higher than your chest measurement. The difference between your chest and bust line measurements is your cup size. A B cup has a bust 2 inches larger than your band measurements, while a C cup has a bust 3 inches larger than your band measurements.

Bra Size Measurement & Cup Size | A, B, C, D, DD Bra Sizes AND Extra Large Breasts


Your breast size can influence how a bra fits and your bust seems. Certain breast shapes necessitate specific bras, and wearing the incorrect one can be uncomfortable and ill-fitting. Also, always get your bra measurements before shopping, and always try on the bra before buying.


Allena is the Founder and Editor of The Better Fit, a platform dedicated to empowering women with practical advice on bras and fitness, inspired by her own revelation of the widespread issue of incorrect bra sizing. Her expertise and tips have been recognized by major publications such as Cosmopolitan, Better Homes & Gardens, Insider, and NBC, making her a trusted voice in women's wellness and lifestyle.