When the four co-founders of Bombas created their startup, they wanted to do more than solely sell socks. The entrepreneurs wanted to donate a pair to homeless individuals for every pair they sold, with the hopes that in 10 years they would give away one million socks.

They hit that target early--by about seven and half years--and continue to surpass subsequent goals they set for themselves five years after the company's launch in 2013. Bombas announced Tuesday that it donated its seven millionth pair of socks.

"From day one, the real origin and DNA of the business was built around solving this problem," David Heath, Bombas' co-founder and CEO, told Inc. Heath and Randy Goldberg, who were colleagues at a lifestyle website, got the idea for their startup while scrolling through Facebook. After learning that socks were the most requested items at homeless shelters--because hygiene, wear and tear make it difficult for people to donate old pairs--they set out to tackle that need. 

First, they needed to build the product. Heath and Goldberg teamed up with Andrew Heath and Aaron Wolk and spent years developing a sock with a seamless toe and a support system that didn't slide down the ankle. Then they teamed up with shelters, non-profit organizations and community programs.

They picked the name Bombas after the Latin word for bumblebee, the industrial insects that work together to better their environment. The co-founders launched the company in 2013 after raising about $145,000 through Indiegogo, and about a year later they pitched the celebrity investors of Shark Tank.

While the other sharks thought the buy-one-give-one business model would be too costly, Daymond John offered the co-founders $200,000 for 17.5 percent equity. From there, Bombas blossomed: the startup brought in $47.2 million in revenue in 2017 and hopes to almost double that by the end of this year.

Bombas isn't the first or only company to incorporate giving into its business model. In fact, the co-founders acknowledge that they borrowed the idea of buy-one-give-one from Blake Mycoskie, the founder of TOMS Shoes. But if an entrepreneur's goal is to build a startup with a similar philanthropic model, Health says the founder must find a meaningful cause and show customers they are genuine about the mission.  

"Don't just do it for marketing purposes, go out and volunteer and experience whatever problem that you're trying to solve first hand," Heath says. "You have to get close to it in order for it to feel authentic."