what is the cost of a stamp to mail a letter
1 USPS Tracking when purchased online will cost $0.36 in 2015, compared to $0.23 in 2014. 2  Postage for First Class Mail International Letters (1 oz.) and postcards will increase by five cents from $1.15 to $1.20. 3  First Class Package International Service will see an increase of 7.2% in 2015. 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.