Computers and Electronics Can a 16 year old workout at Planet Fitness? Can a 16 year old workout at Planet Fitness? *Teenagers ages 15 – 18 can visit any Planet Fitness location in the United States. ... Teens under 18 must bring a parent or guardian to sign up. Once the parent or guardian waiver is signed for teens under 18, teens can workout alone.Apr 26, 2019 Related Posts:How old do I have to be to go to Vasa?What gym has a free trial?How To Write a Will When You Have ChildrenDo Planet Fitness employees get paid weekly?