how to check car blind spot

[Jill]

The most effective way to check your car's blind spots is to perform a simple, three-step process: adjust your mirrors correctly, perform an over-the-shoulder "head check," and use available blind-spot monitoring technology. Properly set side mirrors drastically reduce the area your eyes can't see. According to the Society of Automotive Engineers (SAE), the correct method is to angle your side mirrors outward so that your own car is just out of view, which significantly minimizes blind zones compared to the traditional method of seeing the side of your car.

While mirror adjustment is the foundation, the physical head check—glancing over your shoulder to see the area next to and slightly behind your car—remains the most reliable method. This is crucial before changing lanes or merging.

Modern vehicles often come equipped with Blind Spot Monitoring (BSM) systems. These use radar or ultrasonic sensors to detect vehicles in your blind spots and alert you with a visual warning on or near your side mirrors. Some systems also provide an audible alert if you attempt to change lanes while a vehicle is detected.

NHTSA Blind Spot Crash Data (2019)

Crash Scenario	Estimated Annual Injuries	Key Contributing Factor
Lane Change/Merging	50,000	Failure to properly check blind spot
Backing Incidents	15,000	Limited rear visibility (especially for SUVs/trucks)
Pedestrian/Bicyclist	9,000	Blind spots obscuring vulnerable road users

No single method is foolproof. The safest approach is to use all three techniques in combination: rely on your properly adjusted mirrors for an initial scan, always complete a quick head check for confirmation, and use your BSM system as an extra, valuable warning. Remember that technology can fail, so never rely on it exclusively. Developing this habit is essential for defensive driving.

[OwenAnn]

It’s simple. Lean your head against the driver’s side window. Now, adjust your left mirror until you can just barely see the side of your car. For the right mirror, move your head to the center of the car, above the console, and adjust that mirror the same way. This gets rid of a huge chunk of the blind spot. After that, it’s all about the quick look over your shoulder before you move. That little glance is your best friend on the highway.

[OKayden]

Honestly, the best thing I did was get those little convex blind spot mirrors from the auto parts store. They stick right on the corner of your main mirrors. It’s a cheap fix that gives you a much wider view and practically eliminates the blind spot on the passenger side, which is the hardest to check. I still do a head check, but these little mirrors give me extra confidence, especially when I’m towing my camper and my view is even more limited. It’s a low-tech solution that works incredibly well.

[Finn]

I’ve found that most people’s mirrors are set wrong, pointing right behind them where the rearview mirror already looks. The key is to set them wider. When you’re driving, a car passing you should move from your rearview mirror to your side mirror, and then into your peripheral vision. If it disappears from the side mirror and pops up in the blind spot, your mirrors are too narrow. Properly adjusted, the side mirror should show the adjacent lane, not the side of your own car. This creates a seamless transition of visibility.

[BraxtonAnn]

My car has the blind spot warning lights, and it’s a fantastic feature. The little orange light on the mirror flashes if someone’s there. But I don’t trust it 100%. I treat it as a backup. My routine is: check the rearview, check the side mirror, glance over my shoulder, and then I also notice if the warning light is on or off. Technology is great, but you’re still the driver in charge. It’s an extra layer of safety, not a replacement for your own eyes and awareness. Always verify for yourself before making a move.