A letter scale is a weighing scale used for weighing letters in order to determine the correct amount of postage. Until the 1990s most letter scales were mechanical, but today electronic scales are the most common.

Letters are also categorised by their measurement in height. For instance The letter 'h' stands far taller than 'o'; therefore 'h' is an A class letter whereas 'o' is a C class letter. The tallest of all letters is 'Y' (a B1 class letter).

Article Comparing and explaining letter scales

fr:Pèse-lettre