Yikes, no!

A fraction of a millimeter can determine whether or not a seat post fits. Get a dial caliper if you don't already have one. Or you could try an auto parts store with customer tools...the Advance Auto by my house didn't have one, but loaner tool inventory varies from store to store. And if all else fails, you could probably get your LBS to measure it for you for free. All it takes is a few seconds to adjust the dial, so they'd be crooks if they charged you for that.