Check the weight of the envelope or package
Measure the size if it is unusually large or thick
Identify the destination as local, domestic, or international
Look up the current postage rate from your postal service
Compare the item’s weight and size to the postage chart
Add extra postage for nonstandard shapes, rigid contents, or bulky items
Use a postage calculator on the postal service website
Ask at the post office if you are unsure
Round up with an extra stamp if the total postage is close to the next rate
Verify that the total value of stamps matches the required postage amount