This very much depends on the individual.  It is possible to fit contact lenses to very young children – even infants – so there is no reason on age grounds alone that a 13 year old cannot wear lenses.  What is more important are issues such as whether your prescription is changing rapidly and whether you are prepared and able to maintain the required cleaning schedule and aftercare check-ups advised by your optician. Call in at your local optician to discuss your vision requirements and to find out if lenses would be suitable for you.