I send out 6x8 envelopes to the US and I use one $1.20 stamp! Hopefully this helps

Canada Post have a calculator in their website. You can order stamps from them too.

Ok.. I'm from the states and looking for some help from anyone in Canada... I have a 5 x 7 photo mailer that I use as a S.A.S.E. The problem is that here in the states we have a different system for postage. I guess what I'm asking is what would be the postage be for one of these? It's about 3oz. after I put the pictures inside it.. What is the postage rate for one of them there in Canada? It's very thin no bulk at all. I have a few people I want to request autographs from that are in Canada right now. And want to make sure I have enough postage for the return.
The mailer is a cardboard 5 x 7 so the pictures will not get bent.

Thanks for all your help....I'm new to all this