I've surfed a variety of who-is sites and am not finding this.

To be honest, I'm trying to confirm it for some of mine but none of them are with the original company that I registered them with.

Is there any way to tell how long someone has been the registrant of a domain name?

Thanks!

To clarify. I do see "creation date" with the info here, but I am positive that I first registered it with someone else earlier than the date shown.

I don't believe this information is kept, the only place you could check is with the company you were registered with before.. :/

You can check the domain info from here ZippoZap Domain Whois Search this site provides accurate whois information including the domain created date and expiry date. You can easily calculate the age of a domain from the date of creation.