How much is a 1926 dime worth?

You'll need to have an idea of the coin's condition, and check to see if there's a mint mark next to the Word ONE on the back of the coin. It may be blank, or have a small D or S. Note - the "W" on the coin's face is the designer's monogram, NOT a mint mark!

A very rough explanation of the grades is:

G4 means that the coin is quite worn but major details are visible

F12 means that the coin is somewhat worn but most details are visible

VF20 means it is slightly worn

XF40 means it has almost no wear

Then check the page linked below for an approximate retail value.