How to Check Your Oil Level
Another five-minute check you can do yourself under the bonnet — reading the dipstick correctly and knowing when to top up.
Read the guide →
Replacing wiper blades is one of the cheapest, quickest car jobs you can do yourself, and one of the few that directly affects how well you can see in the rain. What puts most people off isn't the job. It's the fear of buying the wrong size, or of the bare metal arm snapping back and cracking the glass. This guide deals with both. It covers how to tell when blades are worn out, how to find the sizes your car needs before you buy, and how to swap them safely, with one simple precaution that protects the windscreen.
What you'll be able to do: Recognise worn wiper blades, buy the correct sizes for your car first time, and replace and test them yourself in under 15 minutes.
Outcome: "I can tell whether my wiper blades need replacing, and I have the correct sizes and connector type written down before I buy."
Spray washer fluid on the windscreen and run the wipers for a few sweeps. Watch the glass, not the wipers: look for streaks, smears or patches they miss.
Wiper blades are rubber, and rubber hardens and cracks with sun, frost and use. Many blade makers suggest replacing them roughly every 6 to 12 months, but the glass tells you more than the calendar. Replace them when they leave streaks or a smeared film, miss the same patch on every sweep, skip or judder across the glass, or squeak. Also check the rubber edge by lifting the arm and running a fingertip along it. Splits, a rounded edge or rubber peeling away from the frame all mean it's time. Most cars use two different lengths, a longer blade on the driver's side and a shorter one on the passenger side, and many also have a rear wiper. You can find your sizes in the owner's manual, in a parts store's lookup by make, model and year, or by measuring the old blades end to end. The other thing to check is how the blade attaches to the arm. The most common connector is a J-hook, where the end of the arm curls into a hook shape. Many replacement blades come with adapters for several connector types, but checking first saves a second trip.
A driver notices a smeared arc in their line of sight every time it rains. They lift each arm and find the driver's blade rubber split near one end. Before going to the shop, they measure both old blades and get 24 inches for the driver's side and 18 inches for the passenger side, and see that the arms end in J-hooks. They check the same numbers in a parts store's online lookup for their make, model and year. Both match, so they buy a 24-inch and an 18-inch blade, both listed as J-hook compatible.
Outcome: "I can lift the wiper arm, release the old blade and remove it, without the bare arm ever hitting the glass."
Lay a folded towel on the windscreen below one wiper, then lift that wiper arm away from the glass until it stays up on its own.
The one real risk in this job is the bare wiper arm. It's spring-loaded, and if it snaps back onto the glass without a blade on it, it can chip or crack the windscreen. So before you remove anything, lay a folded towel on the glass under the arm, and keep a hand on the arm while the blade is off. Some cars need the wipers moved to a service position first because the arms rest under the edge of the bonnet. The owner's manual explains how for your car, often by switching the wipers on and off again right after turning the ignition off. Lift the arm until it holds itself away from the glass. On a J-hook arm, the blade is held by a small plastic clip in the middle where the hook passes through. Turn the blade so it's at a right angle to the arm, press the release tab on the clip, and slide the blade down towards the base of the arm, out of the hook. If it doesn't move, look for a second tab rather than pulling harder. Other connector types work differently, but the packaging of the new blade usually shows how its connector releases.
Halfway through removing the first blade, someone lets go of the arm to get a better grip on the clip. The arm snaps back down, but lands on the folded towel they had laid out, and the windscreen is untouched. After that they keep one hand under the arm the whole time the blade is off. On the second side they find the release tab, slide the blade down out of the J-hook in one smooth move, and lower the bare arm gently onto the towel.
Outcome: "I can fit the new blade so it clicks securely onto the arm, and test it properly before driving."
Take the new blade out of its packaging and find its connector and any adapters. Match the one that fits your arm's hook before you go near the car.
Fitting is removal in reverse. With the bare arm held up, and the towel still on the glass, line the new blade's connector up with the hook and slide it up into the hook until it clicks. The click matters. A blade that isn't fully locked can come off at speed in heavy rain. Give it a firm tug along the arm's direction to confirm it's secure, then lower the arm gently onto the glass. Then test it: spray washer fluid and run the wipers at each speed. A new blade should clear the glass in one clean pass with no streaks. If it judders, check that it's sitting flat on the glass and clicked fully home. If it streaks straight away, the windscreen itself may be dirty or waxy, so clean the glass and the new rubber edge with washer fluid on a cloth and test again. Do the driver's side first so you always have one working wiper. Then do the passenger side, and the rear wiper if needed.
A new driver's-side blade seems to be on, but during the test it chatters and leaves a band of water at the top of the sweep. Lifting the arm shows the connector only halfway into the hook. They slide it up until it clicks, tug it to confirm, and lower the arm. The next test clears the screen in one pass. The passenger blade goes on with a clear click the first time, and the whole job takes twelve minutes.
The complete guide — all 3 chapters, every checklist and exercise — as a clean, printable PDF. No email required.
Every guide on this site is produced with the Self-Directed Learning Framework: instead of an article that explains a topic at you, the framework turns it into a structure you work through — each chapter with one outcome, a starting action under twelve minutes, the minimum you actually need to know, a worked example, a checklist, and exercises. It starts from three questions:
Topic: Replacing a car's windscreen wiper blades.
Outcome wanted: Replace both front blades (and the rear, if any) without help — within three days, buying the right sizes first time.
Starting point: Drives regularly, has never replaced a part on the car, and worries about buying the wrong size or damaging the glass.
The prompt framework behind it is public: see the C.R.A.F.T. prompt framework, including the exact prompt that generated this library.
Another five-minute check you can do yourself under the bonnet — reading the dipstick correctly and knowing when to top up.
Read the guide →Free, self-paced guides across everyday, professional and academic topics.
See all guides