My new critique group had questions on getting the postage right on a SASE included in a query to an agent in the U.S. We seem to be mostly Canadians so the question was: how to calculate the postage correctly and obtain the stamps for a SASE sent by the agent back to the writer in Canada.
I've had nothing but success with the US Postal Service website.
Here are the steps:
1) Put a single sheet of paper in a standard envelope, go to your local Canada Post outlet, put the envelope on their scale, and record the weight in grams.
1b) If you want your materials returned to you as well, put those in a 9x12" envelope, put that on the scale and record the weight in grams.
2) Ask Canada Post for a sheet or two of Air Mail/Par Avion stickers. These are free.
3) Use whatever converter you have and convert the weight to ounces. My Mac's dashboard widgets have a converter built in.
4) Go to the USPS website and use their rate calculator to figure out the postage rate for a letter or package sent from the U.S. to Canada. I use the Airmail Letter Post rate. It's even cheaper than Economy Surface! At the time of this writing, the Airmail Letter Post rate for a simple letter weighing up to 1 oz was 63 cents U.S.
5) Order stamps from the USPS website. They will ship them to Canada. The service charge is fairly pricey, so if you're planning on sending a bunch of queries, buy in bulk.
6) Place correct U.S. stamps on your SASE. If you're using the Airmail rates, be sure to stick on an Air Mail/Par Avion sticker as well.
I've never tried using an International Reply Coupon. I heard they require the sender to go down to a post office to use them, and I've heard agents hate doing that. I've been using this technique and have gotten over 90% of my queries back.
Now I just have to improve the rejection ratio :-)