ThirdLove

ThirdLove is an American bra company founded in San Francisco in 2013 by Heidi Zak and David Spector, who ran it as co-CEOs. It sold its first bras in spring 2014, online only, and made its name with half-cup sizes and an online fit questionnaire that replaced the fitting room with a set of multiple-choice questions. The company also credits Ra'el Cohen, the lingerie designer who built its first prototype, as a co-founder.

A Google Ad Executive and a Spreadsheet Problem

Zak came to bras from advertising. She left a job on Google's advertising side to start the company, and the pitch she and Spector took to investors was the language of that world: measure the customer, find where the product fails, and fix the gap in the data. Their first gap was cup size. ThirdLove's research claimed that standard cup sizes did not fit 37 percent of women, many of whom sat between two letters.

The answer was the half cup. Instead of jumping from a B to a C, ThirdLove added a B 1/2, a C 1/2 and so on, which multiplied the number of sizes without changing the familiar band and letter system. The company describes itself as having made "the first bra to come in half cup sizes." That claim is the brand's own and hard to test against a century of custom corsetry, but no mass-market label had built a business on half sizes before it.

FitFinder

The second piece was the FitFinder quiz. A shopper answered questions about her current bra and how it fit, and the site recommended a size and a style. It was a fitting session reduced to a form, and it gave ThirdLove two things at once: a reason for first-time buyers to trust a size they had never worn, and a growing set of fit data that a store-based competitor could not easily collect. The company now calls the tool a virtual fitting room and says it takes about two minutes.

Money and Momentum, 2013 to 2019

ThirdLove was funded on a Silicon Valley schedule. A seed round of $5.6 million in 2013 brought in NEA, Andreessen Horowitz, Yuri Milner, the fashion investor Silas Chou and Nasir Jones, among others. NEA led an $8 million Series A in 2016. In 2019 L Catterton led a $55 million Series B, with Anne and Susan Wojcicki and Tim Armstrong also investing. That is about $68 million in disclosed venture money in all. In October 2018 Forbes valued the company at $750 million.

The product range widened with the money. In June 2018 ThirdLove added 24 larger sizes, pushing the count toward 70. The best seller became the 24/7 Classic T-Shirt Bra, a molded T-shirt bra that the company says was developed on real bodies rather than a fit model.

The Letter to Victoria's Secret, November 2018

ThirdLove's best-known moment was a piece of print advertising. In November 2018 Ed Razek, the chief marketing officer of L Brands, gave an interview defending the Victoria's Secret fashion show and dismissing the idea of casting plus-size or transgender models. On November 18, Zak answered with a full-page open letter in The New York Times, addressed to Victoria's Secret, arguing that the bra market had moved on from a fantasy written for men and that women wanted bras built for their own bodies.

It was a cheap stunt by the standards of national advertising and a very effective one. The letter ran at exactly the moment the older company's show was losing its audience, and it placed ThirdLove, a five-year-old online brand, as the face of the alternative. The fashion show was cancelled the following year.

Beyond the Bra

ThirdLove opened its first physical shop as a pop-up in Manhattan's Soho in July 2019; it stayed open until March 2020. From 2021 the brand pushed into new categories: a seamless wireless bra line, then underwear, loungewear, sportswear and sleepwear. That year the market researcher NPD Group named it the third-largest online intimate apparel brand in the United States.

The company also runs a large giving program and says it has donated more than $50 million worth of product to people in need.

Zak remains chief executive. The brand's own copy still leads with the half cup, which is the right instinct: a decade of rival direct-to-consumer labels has copied the quiz, the free returns and the inclusive casting, but the B 1/2 is still the thing a customer remembers.

Last updated October 7, 2026