The standard postcard size ranges from 3.5" x 5" to 6.125" x 11.5". Any sizes that will not fit within this range will not be processed by the Post Office.
If worried about the size of your postcard, a standard postcard is measured 4 by 6 inches. Postcards can actually be any size so they can be different in any country.
The standard size for a postcard is 4x6" and the biggest size is 6x11". I am not sure if there are postcards smaller than the 4x6".
The postage for a postcard is valued at $0.33 as of 2014. This can vary depending on the size of the postcard and may change as the Postal Service changes its rates.
The layout of a postcard must follow specific USPS guidelines. These guidelines include size, zones that designate where the sender's address goes, and proper layout.
1 inch and a one tenth
To mail a first class international postcard to Canada, you will need to attach $1.10 in postage. The maximum size for a postcard is 6" in length x 4.25" in height.
The standard size postcard is 4" X 6".
As of July 2011, the rate is $0.29.
Any square unit you like can be used to measure the area of a postcard, however to make the numbers have a reasonable size and ease of handling, I would suggest using square centimetres as a postcard is about hand size (and likely to be about 15cm by 10cm).
According to the USPS website, the Maximum size for postcards is 6" long x 4-1/4". As long as you stay within this size, you're postcard will be okay to send. You may want to double check with your local post office to be sure.
The standard size for a postcard in the United States is at least 3 1/2 inches high by 5 inches high. But no more then 4 1/2 inches high by 6 inches long.
Well the standard size of a postcard is 4 x 6, but there are some that come in sized relatively larger. These do require extra postage though, usually.