Wiper Blade Sizes: Millimetres to Inches
Wiper blade sizes in owner's manuals are usually printed in millimetres or centimetres, while the blade on the shelf is labelled in whole inches. The two do not match exactly: a 600 mm blade is 23.6 inches long, yet the box says 24 inches.
Why the numbers differ
Blade makers size blades in 25 mm steps and call each step one inch. That is close to the true inch (25.4 mm) but not equal, so the nominal size drifts away from the exact length as blades get longer. The wiper size table on this site shows both numbers for every car whose manual prints a length.
| Printed length | Exact inches | Blade size sold |
|---|---|---|
| 300 mm | 11.8 | 12 in |
| 400 mm | 15.7 | 16 in |
| 450 mm | 17.7 | 18 in |
| 500 mm | 19.7 | 20 in |
| 550 mm | 21.7 | 22 in |
| 600 mm | 23.6 | 24 in |
| 650 mm | 25.6 | 26 in |
| 700 mm | 27.6 | 28 in |
What the manuals print
Of the model years on this site, 51 print wiper lengths. The most common driver-side lengths are 550 mm (20 model years), 600 mm (16 model years), 650 mm (12 model years), 625 mm (3 model years). GM prints centimetres with inches in brackets, Tesla prints both inches and millimetres, and Ford prints Motorcraft part numbers instead of lengths. Toyota, Honda and Nissan usually print no length at all, so for those cars measure the old blade from end to end.
Choosing the blade
- Find your model year under Cars and read the driver, passenger and rear lengths.
- Buy the sold size shown, or one size shorter if that size is out of stock. Never go longer on the driver side.
- Match the connector to the wiper arm (hook, pinch tab or side pin). The length printed in the manual says nothing about the connector.
A blade that is one size too long can strike the windshield pillar at the end of its sweep or overlap the passenger blade, which is why the shorter choice is the safe one when the converted wiper blade size falls between two inches.
Sources
- Wiper lengths: each car's official owner's manual, cited with its page on the car's page.
- Conversion: 25.4 mm per inch; trade step 25 mm per nominal inch, as used on blade packaging.
Questions
Is a 600 mm wiper blade 24 inches?
It is 23.6 inches long, and it is sold as a 24-inch blade because blade sizes step in 25 mm per nominal inch.
Can I fit a longer wiper blade?
One size shorter is safe; a longer blade can hit the windshield frame or overlap the other blade.