What age would you have to be to sign up?

You can join PF starting at the age of 13 with a parent/legal guardian’s permission; they must be present with you during the sign-up process. Members between the ages of 13 and 15 must be accompanied by a parent or guardian when they work out. Members who are 16 or 17 years old must have a signed waiver from a parent or guardian on file. Please note that any PF Black Card® guests must be 18 years old with a valid ID, unless they’re accompanied by a parent or guardian. See more here: https://www.planetfitness.com/about-planet-fitness/customer-service/membership-faqs

You have to be 18 .