How do I find my wiper blade sizes?

Steps

1. Park on level ground and lift the driver-side wiper arm away from the glass until it clicks into the service position, or lay a folded towel under the arm so it cannot spring back and chip the windscreen.
2. Lay a flexible tape measure along the rubber wiping edge, from tip to tip, following the curve. Read the length in millimetres. Ignore the plastic end caps or spring housing beyond the rubber itself.
3. Repeat for the passenger blade. On most modern cars the two are different lengths, so measure both and write both down.
4. If your car has a rear wiper, lift that arm and measure the rubber edge the same way. Rear blades are usually 250 to 400 mm and take a completely different attachment style.
5. Look at the end of each wiper arm with the blade removed. A hook shape is a J-hook. A squeeze tab that releases with a pinch is a pinch tab. A small horizontal pin is a side pin. Note which style each arm uses.
6. Cross-check both lengths and the adapter style against the owner's handbook, usually in the maintenance or consumables chapter. If the handbook lists inches, divide your millimetre figure by 25.4 and round to the nearest common inch size.

What you need

• A flexible fabric or steel tape measure, at least 750 mm long.
• A folded towel or microfibre cloth to protect the windscreen while the arms are lifted.
• A torch to inspect the arm end fitting in low light.
• The owner's handbook or the vehicle handbook PDF for cross-checking.

Common mistakes

• Measuring the plastic end caps or the spring housing as part of the blade. The number you want is the rubber wiping edge only.
• Assuming the driver and passenger blades are the same length. Fitting two matched blades either leaves an unswept wedge on the driver side or catches the A-pillar on the passenger side.
• Letting the raised arm snap back onto bare glass. Wiper arms are spring-loaded and a bare pivot on a cold windscreen can crack it. Always keep a towel under the arm until the new blade is fully engaged.

Frequently asked questions

Do I measure the whole blade or just the rubber?

Measure only the rubber wiping edge, tip to tip along its length. The frame or spring housing at each end adds a few millimetres you should ignore. That rubber length in millimetres is what the box and the owner's handbook both refer to.

The driver and passenger blades are different lengths, is that normal?

Yes, on almost every modern car. The driver arc is longer to sweep the driver's field of view, so the driver blade is typically 550 to 700 mm and the passenger blade 450 to 550 mm. Measure both, and never assume a matched pair.

How do I know which adapter my arm uses?

Take the old blade off and look at the end of the wiper arm. A hook shaped like a J is the classic J-hook. A rectangular tab you squeeze from the side is a pinch tab. A small pin sticking out sideways from the arm end is a side pin. Most modern replacement blades ship with a multi-adapter that covers all three, but the box will list what is included.

My handbook lists a length in inches but the blade box is in millimetres, how do I convert?

Multiply inches by 25.4 to get millimetres, or divide millimetres by 25.4 for inches. Common sizes: 400 mm is 16 inch, 450 mm is 18 inch, 500 mm is 20 inch, 550 mm is 22 inch, 600 mm is 24 inch, 650 mm is 26 inch, 700 mm is 28 inch. Round to the nearest common size, not up.