What is the postage of a 8.5 x 5.5 postcard?

If its 8.5 inches wide and 5.5 inches high, the postage would be 44 cents. But if its 8.5 inches high and 5.5 inches wide, the postage is more. (I'm not sure what the current "oversize" surcharge is. That can be found on the USPS website.)