The system we are using is wolf years (I think). Five wolf years would be a little over one human year, I believe. Stryder put his character age at 21, which (in his words) is essentially 4 human years (it's actually 4.72 human years. He should have rounded that up).

This calculator should help:
[url=http://easycalculation.com/other/fun/Wolf-years-to-Human-years.html]Calculator[/url]