You can join Planet Fitness 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 Planet Fitness Black Card guests must be 18 years old with a valid ID unless they’re accompanied by a parent or guardian.