Sending something by Royal Mail?Need to know if its a letter, large letter or packet?Then "Postage Checker" is the app for you!This app is for people sending items via Royal Mail. It allows you to know if your is a letter, large letter or packet and the postage cost. This is done by entering the item’s length(mm), width(mm), thickness(mm) and weight(g) then choosing 1st or 2nd class. It is advisable to use this as a guide before going to your local Post Office.