Wiper blades are sized in inches and finding the standard measurement of your blades is easily accomplished. Wiper manufacturers frequently have sizing guides on their websites and auto parts stores and discount retailers often provide sizing catalogues in their windshield wiper department. If you do not have access to these resources, you can determine the size of your wiper blades by using a tape measure. Be sure to measure both driver side and passenger side wipers, as they usually differ.
Lift the driver side wiper blade off of the windshield.
Press on the blade so that the blade itself is flat, as opposed to curved.
Measure the wiper blade from end to end with a tape measure.
Jot the measurement down, and lower the blade back to the windshield.
Repeat this process with the passenger side blade. The passenger side blade will likely have a smaller measurement.