Webplanet fitness age requirements explained • age at planet fitness • find out how strict planet fitness is about age restrictions and what is required for min. Webplanet fitness is a judgement free zone® where anyone can join and work out. The web page does not mention any age requirement for membership, but it has policies on non. Webno one under 13 is allowed in the gym. A 12 year old can walk up to the front desk but that’s as far as they can go. Webfind answers to common questions about planet fitness membership, such as how to cancel, transfer, upgrade, or downgrade your membership, and how to pay with.