cost of extra ounce stamp
Summary of the 2015 Postage Rate Increase: 1  First Class Mail Letters (1 oz.) will remain the same at $0.49 when purchased at the Post Office. 2  Each additional ounce will cost $0.22 (up one cent from 2014). Each additional ounce will cost $0.22 (up one cent from 2014). 2  Postcard rates will increase by one cent to $0.35 from $0.34. 3  Media Mail will see an increase of 6.2% in 2015. 4  Rates will start at $2.72 (1 lb.), up $0.03 compared to 2014.