what is the rate of a first class postage stamp
1 Each additional ounce will cost $0.22 (up one cent from 2014). 2  The discounted âMetered Mailâ category for First Class Mail Letters (1 oz.), which includes online postage providers and postage meters, will increase from $0.48 to $0.485 in 2015. The discounted âMetered Mailâ category for First Class Mail Letters (1 oz.), which includes online postage providers and postage meters, will increase from $0.48 to $0.485 in 2015. 2  First Class Flats (1 oz.) will stay the same at $0.98 in 2015. 3  Each additional ounce will cost $0.22 (up one cent from 2014).