My friend in Japan has a birthday next Saturday. I sent her a card today (air mail.) Does anyone know the average time it takes for mail to get from here to there?
Try the USPS’s Postal Rate (and Delivery Time) Calculator.
Here’s a sample chart for an 1-ounce envelope sent to Japan. It says the letter should take 4 to 7 days to arrive.
That also matches my experience, assuming the address was written correctly.