How A Whole Lot Of Data Led To Half Cups

"My friends and I all had a favorite brand for almost everything—shoes, jeans, beauty products," ThirdLove co-founder Heidi Zak realized, "but not bras."

“And it was no wonder: between too-tight bands, slipping straps, poking underwires, itchy tags, and saggy cups, really, what’s to love?” That’s when Heidi knew something had to change. Bras were broken, and she was determined to fix them.

From the company’s earliest days, she set out to define the ThirdLove bra experience around real women—and real data. Teaming up with experienced lingerie designer Ra’el Cohen, the duo did their homework, collecting as much information as possible on bras and the women who wear them. They assessed the fit of various US and European brands, ran bra-fitting focus groups with hundreds of women, and even developed a Fit Finder to help women find their bra size from the comfort of home. What they found was stunning.

First, here’s why most bras don’t fit: You’re not Dorothy.

A 1970s cabaret singer, Dorothy Galligan became the go-to bra model for decades because she had, according to the industry, the perfect size and shape 34B breasts. A little-known fact about bra-making is that all bra prototypes are fitted on models who are a 34B and then sized up and down from there. In fact, the majority of bras are fitted to exactly one woman’s 34Bs: Dorothy’s. Great for Dorothy, but not as great for all the other women out there.

Second, over a third of women actually fall in between standard cup sizes. “That was our major aha moment,” says Ra’el. “The old principles of bra design weren’t working for a huge number of women. The whole thing had to be rethought.” ThirdLove’s solution? Half-cup sizes.

Other details emerged from the research as well, like the center front gore (the part of the bra between the cups) needs to be larger or smaller depending on the cup and band size. The same goes for strap length: its scale had to accommodate the bra size.

Armed with these insights, Heidi and Ra’el knew ThirdLove would be the first company to create half-cup sizes. But in order to get the bras made, they had to convince a factory to work with them. Not only do other bra companies stick to the standard sizes, they use pre-made, uniform cup molds, which makes the fabrication cheap and efficient. It also means the same poor fit is often replicated across bra brands.

Heidi and Ra’el were determined to create half-cup sizes and to design their own proprietary cup molds, making the process far more time- and cost-intensive. Each new cup mold is an increased cost, and adding half-cup sizes to ThirdLove’s selection means creating 50% more cup sizes than normal. “Every factory we met with looked at us like we were crazy,” says Ra’el.

According to the industry, they were crazy. The bra market is dominated by a few big corporations, all with men at the helm. The focus is on cost, because without top decision-makers experiencing the literal pain points of an ill-fitting bra, the justifications for investing in fit just aren’t as compelling. "Most of them think, 'How do we shave 5 to 10 cents off this garment?'” says Heidi, “but we knew, from our research—and our own experience—that we had to prioritize fit.”

After a long search, Heidi and Ra’el found an innovative factory in China who saw the potential in their ideas—and the importance in the details. Working with the factory’s R&D team, ThirdLove developed proprietary custom memory foam cups in whole and half sizes, a unique padded hook and eye closure, a tagless label, and other specifics that would make ThirdLove bras revolutionary in terms of fit, feel and style.

The bras were ready to hit the market, but the research wasn’t over. ThirdLove prototyped seven different bras to see which one resonated best with customers. A clear winner emerged: the 24/7 bra, still the top-seller today. The 24/7 bra is available in six styles, with rave reviews from customers, and data still informs how the bras are made. At ThirdLove, design is an ongoing process and “our fit gets better as we grow because of the data we collect and what we learn from customer feedback," says Heidi.

Around 35% of ThirdLove’s bra sales today are half-cup sizes—a huge percentage of the company’s customer base. And with all of ThirdLove’s cup sizes having been designed from scratch, it’s safe to say that 100% of their customers are wearing a fit that can’t be found anywhere else.

Now that they’ve broken the mold on bras, what’s next for ThirdLove? “What I think about is the bigger picture: ‘What’s next for women?’” says Ra’el, “when women are comfortable and supported, they can take their mind off their bra and accomplish amazing things. And I love being a part of that.”