What is the best postcard size?
The best size for your postcard ultimately depends on where and how it will be delivered. Postcards sent to regular mailboxes can be as large as 6 inches by 11 inches or more. You could go as large as 13 inches by 17 inches, though this size won’t fit in most standard mailboxes and will need to be folded. All in all, a 5-inch by 8-inch postcard or a 6-inch by 9-inch postcard is large enough to stand out from the standard 4-inch by 6-inch postcard pack, so simply adding a few inches can be just the trick you need to put your return on investment over the top.
