The lightest 1LP packaging I've got is around 1 lb 1 oz. To be safe I might do 1 lb 6 oz. That said, a kitchen scale is inexpensive and a worthwhile investment!
@kvetcha thanks! i have a kitchen scale but my printer is at work so trying to take advantage of printing it myself hah. Forgot to weigh before I left this AM.
I would err on the side of doing a little more, so like 1.5 lbs. Media mail is so cheap I'd rather pay the extra 50 cents or whatever it is.