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So You're A 40D...What's That Even Mean?

So you measured yourself using our Size Calculator, maybe tried on a few bras, read all about how your bra is supposed to fit correctly - and you have determined you wear a size 40D. Great! But what does that actually mean? Trusst is based on science and technology, and we’re always fascinated with problem-solving and learning new things. We thought it would be fun to put together some interesting data and facts around this 40D number so that you can really get to know your size - because it’s not just a’s a lifestyle.

Cup Volume

As a 40D your breasts weigh about 4 pounds. That’s a lot of weight to carry around! Good thing you have Trusst’s bra support technology to do the heavy lifting and take the pressure off your back and shoulders. 

Band Size + Sister Sizing

Trusst bands fit true to your underbust measurement, which means that you measure within a range of 38.5-40.5 inches. As you have probably learned by now, your band should fit snugly (but not too tight!) and should lay parallel to the floor. If it is too loose and riding up, it might be time to size down in the band. This methodology of sharing sizes is called “sister sizing.” Each sister size has the same cup volume but is called something different. 

The cup volume of a size 40D is also the same as a 38E. So if the cup volume works for you, but the band feels too loose, you might want to try out a 38E. Vice versa - if the band feels too tight, you might want to size up in the band. Here are the Trusst sister sizes to your size 40D: 38E and 42C. Although we don’t offer bras in one of these sister sizes, our production team is currently working to expand sizing.

Our Favorite 40D Bra

Our favorite 30D bra is the Evie front closure bra, which features an easy to wear front closure hook and a breathable mesh racerback. It also has a wider sideband for a smooth and comfortable fit. 

Still have questions about your size? Email us at and our Bra Experts will gladly speak with you about your bra options or help you with fit advice. Love your Trusst bra? Leave us a review or tag us @trusstbrands with #trusstyourself or #trusststories. We can’t wait to hear from you!

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August 14, 2019 by Trusst Brands
Tags: sizing

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