PFIP LLC (doing business as Planet Fitness) is an American franchisor and operator of fitness centers based in Hampton, New Hampshire. The company reports that it has more than 1,400 clubs, making it one of the largest fitness club franchises by number of members and locations. It markets itself as a "Judgement Free Zone" that caters to novice and casual gym users and is reported to be the nation’s fastest growing fitness center franchise.

Planet Fitness was founded in 1992, in Dover, New Hampshire, when Michael and Marc Grondahl acquired a financially struggling gym and dramatically reduced prices to compete against better-known brands. This low-cost business model focuses on the needs of occasional or first-time health club members, rather than more experienced members.

In 1993, the Grondahl brothers hired Chris Rondeau, Planet Fitness’ current CEO, to work the front desk. Rondeau and the Grondahls recognized that there was a greater opportunity to serve a much larger segment of the population if they changed the gym environment, both in attitude and format, by creating a non-intimidating, low-cost model. Planet Fitness then became known as the “Judgement Free Zone,” aimed more at the average user than the bodybuilder type of fitness enthusiast.

In 2003, Planet Fitness opened its first franchised location in Florida, with Eric Dore and Shane McGuiness.

In February 2016, the franchise was added to the Franchise Times "Fast and Serious" list of top franchises (#1), and in its 2016 ranking of franchises, Forbes magazine ranked Planet Fitness #4 It ranked in the top 50 of the Entrepreneur magazine Franchise 500 in 2017.

In the fall of 2013, TSG Consumer Partners LLC became an equity partner in the Planet Fitness franchise. Michael Grondahl, co-founder of Planet Fitness stepped down as CEO, and was succeeded by Chris Rondeau.

The company reports that as of 2017, there are 58 corporate-owned gyms, the rest independently owned and operated.

The club's two membership levels are $10 and $21.99 per month: the $10 per month level includes access to cardio and strength equipment, unlimited group fitness instruction and pizza and bagels once a month; the $21.99 per month (“Black Card”) level allows members to bring one guest per day at no charge, access to all Planet Fitness locations, and access to extra amenities, such as tanning booths and massage chairs.

In December 2014, Planet Fitness opened its first international location in Toronto, Canada. The second Toronto location opened in early 2015. In October 2015 the company opened their second international location in Santo Domingo, Dominican Republic.

With the addition of a Planet Fitness outlet in Casper, WY, as of August 2017, Planet Fitness had over 1,400 locations with an estimated 10 million members across 49 states, the District of Columbia, the Dominican Republic, and Canada. In 2016, over 90% of Planet Fitness locations were opened by existing franchise owners.

In October 2011, Planet Fitness reached an agreement with NBC to sponsor the network's reality show, The Biggest Loser beginning with the 2012 season. The contestants on the show worked out on Planet Fitness equipment and then at Planet Fitness gyms near their homes, working with Planet Fitness instructors.

In March 2013, Planet Fitness partnered with 50 Cent to sell his energy drink "Street King"

Since December 2014, Planet Fitness has been the official fitness sponsor of Dick Clark’s New Year’s Rockin’ Eve on ABC.

In March 2016, Planet Fitness partnered with STOMP Out Bullying, a national organization dedicated to bullying prevention, and the Boys & Girls Clubs of America to launch the company’s national philanthropic initiative, The Judgement Free Generation. Also in 2016, the company donated more than $1 million to the program. Planet Fitness has also provided mini “Judgement Free Zone” gyms to Boys & Girls Clubs in Manchester, NH and Pasadena, CA.

In October 2011, an Albuquerque Planet Fitness refused to let Tarainia McDaniel wear her religious head covering while working out. Despite signing a two-year contract with the gym, she was turned away and was told the head covering didn't meet the company’s dress code. The woman sued under the New Mexico Human Rights Act and the Unfair Practices Act, asserting that Planet Fitness illegally based the decision to deny her access upon her religion and race (she is African American). The suit further claimed the gym had no legitimate or non-pretextual reason to deny her entry. Planet Fitness denied all violations stating that the Muslim woman failed to participate in good faith and that the company has legitimate business reasons for its practice as well as measures to prevent discrimination. The suit later settled for a confidential amount and Planet Fitness changed its policies nationwide and allows headcoverings.

In March 2015 a Michigan woman had her membership at Planet Fitness revoked after complaining to management that a transgender woman was using the women's locker room at her local gym. The woman said she felt her "safety was being violated" by the presence of a person with "the opposite parts" in a woman's locker room. She later went on to sue the company for revoking her membership, citing violations of her rights to freedom of speech, denial of terms of contract, and denial of access to and use of a public facility. The suit was dismissed in January 2016, the Judge finding that Planet Fitness' policy alone wasn’t sufficient to create a hostile environment.