ThirdLove
An American digitally native lingerie brand focused on fit, comfort, inclusive sizing, and data-informed product design.
Last updated August 31, 2026
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Overview
ThirdLove is an American lingerie and apparel brand founded in 2013 by Heidi Zak and David Spector. The company was created in response to Zak's difficulty finding bras that combined attractive design with dependable comfort and fit. Rather than beginning as a conventional department-store or specialty-retail label, ThirdLove used online commerce, customer research, and digital fitting tools to challenge the standard way bras were sized and sold. The brand's best-known innovation is its use of half-cup sizes. ThirdLove has argued that conventional whole-cup sizing does not accommodate a substantial portion of women, and it developed additional half-cup options to provide more precise fit choices. Its FitFinder quiz uses customer-entered information and questions about existing bras and fit preferences to recommend a size and style. The company also introduced a try-before-you-buy program intended to reduce the uncertainty associated with purchasing intimate apparel online. ThirdLove's early product-development process used photographs and fit information from women recruited through Craigslist, helping the company study how bras fit under clothing and identify recurring problems with conventional products. The first line launched in spring 2014. The business initially manufactured in Mexico, but the cost of importing fabrics contributed to severe financial pressure; it subsequently moved manufacturing to China. The company later expanded its range, including 24 larger sizes in 2018, and built its positioning around body positivity, comfort, and broader size availability. The brand has been primarily direct-to-consumer, although it has also experimented with physical retail. In 2019, it opened a temporary pop-up shop in Manhattan's SoHo neighborhood. Its assortment has expanded beyond core bras and underwear to include loungewear, sleepwear, sportswear, and wireless products. In 2021, ThirdLove introduced a Seamless wireless bra line, reflecting the wider shift toward softer and less structured intimates. ThirdLove attracted substantial venture investment during its growth phase, including a $5.6 million seed round in 2013, an $8 million Series A in 2016, and a reported $55 million Series B led by L Catterton in 2019. The company has remained privately held. In 2021, NPD Group identified it as the third-largest online intimate-apparel brand in the United States, behind Victoria's Secret and American Eagle's Aerie. ThirdLove also became prominent in the public discussion about representation in lingerie after its chief executive criticized comments by Victoria's Secret executive Ed Razek in 2018. Its present brand identity combines online fit assistance, size-inclusive product development, and a comfort-led alternative to traditional lingerie marketing.
History
ThirdLove emerged in 2013 from Heidi Zak's frustration with the difficulty of finding bras that were both attractive and comfortable. Zak left her advertising role at Google and, together with her husband David Spector, pursued a data-led approach to lingerie design. The founders sought to understand how bras actually fit under clothing rather than relying only on conventional industry assumptions. In the company's early research, ThirdLove recruited approximately 100 women through Craigslist and asked them to photograph themselves wearing fitted tank tops over their bras. The resulting visual and fit information helped the company identify common problems in cup shape, coverage, and sizing. Lingerie designer Ra'el Cohen contributed to the development of the initial prototype and the brand's product system. ThirdLove also developed a digital fitting application that evolved into FitFinder, an online questionnaire intended to recommend a bra size and style. A central outcome of this work was the introduction of half-cup sizes. ThirdLove's research and marketing materials argued that standard whole-cup sizes leave many customers between available options. By offering intermediate cup sizes, the company differentiated itself from established lingerie brands and made fit precision a central part of its value proposition. Its first product line launched in spring 2014. The early operating model encountered manufacturing difficulties. Production in Mexico became uneconomic because of the cost of importing fabrics, placing pressure on the young company and contributing to the loss of approximately $400,000 in investment capital. ThirdLove subsequently shifted manufacturing to China. To improve online conversion and reduce the perceived risk of purchasing bras without visiting a store, it streamlined its fitting application and introduced a try-before-you-buy program in March 2015. ThirdLove continued to build its identity around inclusive sizing and body positivity. In 2017, Zak was included in Fast Company's list of the 100 Most Creative People. In June 2018, the company added 24 larger sizes. Later that year, Forbes estimated the company's valuation at $750 million and included it on its Next Billion-Dollar Startup list. The brand's public profile also rose after Zak responded to comments by Ed Razek, then chief marketing officer of Victoria's Secret's parent company, who had said that the Victoria's Secret show would not include plus-size and transgender models. Zak's open letter, published in November 2018, criticized exclusionary marketing and was widely circulated online. The episode became a notable example of a challenger brand using a competitor's controversy to articulate its own positioning. ThirdLove raised venture capital as it expanded. Reported funding included a $5.6 million seed round in 2013, an $8 million Series A in 2016, and a $55 million Series B led by L Catterton in 2019. In the same year, Zak and Spector received an EY Entrepreneur of the Year award for Northern California. ThirdLove also tested physical retail through a SoHo pop-up opened in July 2019 and operated until March 2020. By 2021, NPD Group described ThirdLove as the third-largest online intimate-apparel brand in the United States, behind Victoria's Secret and Aerie. The company launched its Seamless wireless bra line that year. By 2022, its assortment included underwear, loungewear, sportswear, and sleepwear, and the company had expanded its style count from the prior year. ThirdLove remains principally associated with direct-to-consumer lingerie, fit technology, half-cup sizing, and comfort-oriented product design.
- 2021
Seamless wireless line launches
[1]ThirdLove introduces a Seamless wireless bra line and is identified by NPD Group as the third-largest online intimate-apparel brand in the United States.
- 2019
Series B financing and retail experiment
[1]The company raises a reported $55 million Series B led by L Catterton and opens its first SoHo pop-up shop in New York.
- 2018
Larger size range is added
[1]ThirdLove adds 24 larger sizes to its assortment.
- 2016
Series A financing
[1]ThirdLove raises a reported $8 million Series A round.
- 2015
Try-before-you-buy program is introduced
[1]The company streamlines its fitting application and introduces a try-before-you-buy program to address the difficulty of purchasing bras online.
- 2014
First product line launches
[1]ThirdLove launches its first lingerie line in spring 2014 after developing products through customer fit research.
- 2013
ThirdLove is founded
[1]Heidi Zak and David Spector establish ThirdLove as a digitally oriented lingerie company focused on improving bra fit.
- 2013
Seed financing is raised
[1]The company raises a reported $5.6 million seed round from investors including New Enterprise Associates, Andreessen Horowitz, Yuri Milner, Silas Chou, Barry Sternlicht, Munjal Shah, Nasir Jones, and XG Ventures.
Products and positioning
A digitally native, mid-to-premium lingerie brand emphasizing comfort, precise fit, half-cup sizing, inclusive size ranges, body positivity, and data-informed direct-to-consumer shopping.
Bra
24/7 Perfect Coverage Bra
A core ThirdLove bra offering associated with the brand's comfort-led positioning and broad fit system. It is designed for everyday coverage and is marketed alongside the company's size and fit recommendations.
Bra
T-Shirt Bra
An everyday smooth bra intended to sit discreetly beneath fitted clothing. The product represents ThirdLove's focus on practical coverage, comfort, and online fit guidance.
Wireless bra · 2021
Seamless wireless bra line
Introduced in 2021, the Seamless line extends ThirdLove's assortment toward softer, less structured bras. Its launch reflects consumer interest in flexible comfort and wireless support.
Underwear
Underwear
ThirdLove's underwear assortment broadens the brand beyond bras and supports coordinated intimate-apparel purchasing. The category forms part of the company's wider direct-to-consumer essentials business.
Apparel · 2022
Loungewear, sleepwear, and sportswear
By 2022, ThirdLove offered adjacent apparel categories including loungewear, sleepwear, and sportswear. These products extend its comfort and body-conscious positioning into more parts of the daily wardrobe.
Digital fitting service
FitFinder
FitFinder is ThirdLove's online fit quiz. It asks customers about measurements, existing bras, and fit preferences, then uses the responses to recommend a size and style. The service is central to the brand's strategy for reducing uncertainty in online bra shopping.
Controversies
2018
ThirdLove and Victoria's Secret inclusivity dispute
ThirdLove publicly condemned comments by Victoria's Secret executive Ed Razek about excluding plus-size and transgender models from the Victoria's Secret Fashion Show. The dispute was a controversy involving a competitor rather than an allegation of misconduct by ThirdLove, but it became a significant reputational and marketing moment for the company.
Marketing campaigns
- 2018Open letter on inclusivity
United States · Digital
After Victoria's Secret executive Ed Razek made comments rejecting plus-size and transgender models from the brand's fashion show, Heidi Zak published an open letter criticizing exclusionary representation and presenting ThirdLove as a more inclusive alternative.
Outcome. The letter went viral on Instagram and increased ThirdLove's visibility in the public debate over representation in lingerie.
Brand decisions
2021
Launch the Seamless wireless bra lineProduct launchBackground
The company was expanding beyond structured everyday bras and responding to demand for softer, more flexible intimate apparel.
Action taken
ThirdLove launched a Seamless wireless bra line.
Aftermath
The launch broadened the brand's product architecture and supported its comfort-oriented positioning.
2018
Expand inclusive sizingStrategyBackground
ThirdLove's differentiation depended on addressing customers underserved by conventional bra size ranges.
Action taken
The company added 24 larger sizes to its assortment.
Aftermath
The expansion reinforced ThirdLove's body-positive and size-inclusive positioning.
2015
Introduce try-before-you-buyStrategyBackground
Online bra purchases involve significant uncertainty because customers cannot physically try products before ordering.
Action taken
ThirdLove streamlined its fit application and implemented a try-before-you-buy program.
Aftermath
The program was intended to improve customer confidence and online conversion, but the available reference does not provide measured results.
2014
Shift manufacturing from Mexico to ChinaStrategyBackground
The company's initial Mexican manufacturing arrangement created high costs because imported fabrics made production uneconomic.
Action taken
ThirdLove moved manufacturing to China after the early business suffered substantial financial pressure and reportedly lost approximately $400,000 in investment capital.
Aftermath
The move enabled the company to continue developing and selling its initial product line, although the available reference does not provide later manufacturing economics.
Reported investment capital lost. (Early operations before the manufacturing shift)
Recent events
- 2021
ThirdLove launches its Seamless wireless bra line[1]
Product launch · Product generation
The company introduced a Seamless wireless bra range as part of its expansion into softer, less structured intimate apparel.
- 2021
ThirdLove ranked among the leading online intimate-apparel brands[1]
Other
NPD Group identified ThirdLove as the third-largest online intimate-apparel brand in the United States, behind Victoria's Secret and Aerie.
- 2019
ThirdLove raises a reported $55 million Series B[1]
Other
L Catterton led a reported Series B financing round joined by additional investors including Anne Wojcicki, Susan Wojcicki, and Tim Armstrong.
- 2019
ThirdLove opens a SoHo pop-up shop[1]
Other
The online-first brand opened its first pop-up shop in Manhattan's SoHo neighborhood, operating from July 2019 until March 2020.
- 2018
ThirdLove expands its size range with 24 larger sizes[1]
Product launch
The company announced an expansion adding 24 larger sizes, reinforcing its inclusive-sizing position.
Sources3 sources
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