Coating Thickness Gauge: Measuring Car Paint with a Digital Paint Meter

So why should you buy and use a Coating Thickness Gauge or a Digital Paint Meter before you decide to buy a car? here is why all the dealerships are using them and why you should too!

Why you need a coating thickness gauge now!

In the US, millions of used cars are bought every year, with an individual auction location selling thousands of them in a single day. In most cases, buyers do not get enough time to determine the actual value of the car. Sometimes they get less than the value they paid for.

There are also numerous vehicle inspection points, including the paint’s quality, and matching it against the reported vehicle history. The paint’s quality can tell the types of paint damage and whether the vehicle was previously involved in a crash.

In the past, second-hand vehicle inspectors and buyers relied on visual cues that might suggest panel replacement or bodywork. They looked for such things as overspray and poor color finish in particular sections of the vehicle.

Unfortunately, this traditional method was not entirely practical, and subtle variations in texture, color, and gloss would not be detected. This is unless the buyer invested a lot of time to carefully examine the car paint’s thickness in different angles and natural lighting. Visual inspection techniques are significantly ineffective in bad weather and poorly lit areas.

coating thickness meter in action

What is a Coating Thickness Gauge/Meter

The car coating thickness gauge is an innovative device that accurately assesses the paintwork quality. In contrast to the visual inspections, these devices provide quantifiable and reliable measurement results that you can use to make decisions in the yard.

The magnetic pull-off testers were the first practical and affordable paint inspection tools, but they have numerous drawbacks. Their resolution and accuracy are questionable, and they are not useful in determining the paint’s thickness.

The traditional magnetic method assumes that the thickness of the zinc is constant, but nothing could be further from the truth. The zinc coating thickness will vary even within the same car model because of the different suppliers of body components.

Best low budget magnetic digital paint meter + review:
“This is a cool little tester. Attach the magnetic tip to the car and slowly pull away. Watch the color code on the stick and it will tell you if you are looking at a repainted area. First find an un-repainted area which will hold the magnet solid for a bit and that sets your baseline. It should be green or so. Then move around the car retesting. It will surely find repainted areas like it did on my car. One I did not know about!”

The Measuring Principles

The handheld electronic instruments provide the best measure of paint thickness on the vehicle’s body using the various measuring principles.

Typically, the principles are the methods used by thickness meter to determine the paint quality on the various types of car bodies. The different measuring techniques are ultrasonic, eddy current, and magnetic.

But how do the different techniques work? Can you use one method on all vehicle body materials?


Steel is magnetic, and so the ideal instrument to measure the quality of paint is the magnetic gauges using electronic or mechanical operation. The mechanical gauges’ main components are a calibrated spring, a permanent magnet, and a graduated scale. Typically, the mechanical instrument quantifies the force you require to pull the magnet off the surface, thereby determining the thickness of the coat.

The budget pull-off gauges are useful in detecting fillers such as Bondo or other types of filler below the painted surface.

However, detailers prefer electronic magnetic gauges. They are more effective in providing consistent readings by using a constant pressure probe. The electronic meters are hard to influence, and you can be sure the operator is not using some underhand techniques to convince you.

Depending on the electronic gauge model, you can find devices that store the measurement results, analyze and provide a printout. You get the readings on a clear digital LCD.

Eddy Current

If the metal isn’t steel, then the appropriate method to measure the car paint’s thickness is the eddy current technique.

The coil inside the device normally creates an alternating magnetic field when you bring it near a metallic surface. It sets up eddy currents with their own opposing electromagnetic field, which a second adjacent coil senses.

Eddy current gauges are similar to electronic magnetic meters in terms of appearance and operation. You can see the results on an LCD, and you have the option to print the stored results out.

Most devices on the market incorporate both the eddy current and the magnetic current into one device.


Unlike in the past, nonmetal substrates such as fiberglass and plastic as vehicle body materials are now standard. Of course, you cannot use the eddy current or magnetic current on fiberglass or plastic. You use the more expensive ultrasonic device.

The device has an ultrasonic transducer that shoots a pulse through the paint. The pulse reflects back and is converted into an electric signal that tells you the thickness of the coating after analysis. Some of the devices can measure the individual layers in a multi-layer coating.

Best medium budget digital paint meter + review:
“Great product. The case feels well built and the buttons feel strong. It comes with a storage case, battery, calibration plates to ensure accurate measurements and easy to read instructions. Good price and easy to use.”

How to Measure and Use a Coating Thickness on a Car

Ordinarily, vehicles should have the same coating thickness throughout. Any variations should tell you that there is paint blending to conceal touch-ups and repairs. Sometimes, it can be major body works such as welding big parts of the vehicle together.

Use the coating thickness gauge to look for consistent thickness all around the vehicle. Focus on all the seams and note any differences in the paint thickness.

How to Use the Thickness Gauge Reading to Determine a car was in an Accident

Damaged car bodies will always give you problems and shorten the car’s life, no matter how good it has been repainted. Regardless of the cause, a repainted vehicle can have a reduced resale value. Rust damage or crash can substantially increase vehicle repair costs. Use a thickness gauge to determine if the vehicle was ever in an accident.

Usually, the panels, upper areas of fenders, trunk, hood, and lower door edges are prone to rust. The rear quarter panels, the middle area of the fenders, and doors are vulnerable to damage due to accidents and bumps. Focus on them.

You can tell if the vehicle has been repainted by comparing the paint’s thickness with the original paint on the roof. The roof is the least likely to get an accident.

If you notice that the readings in these vehicle parts are thicker than the rest of the vehicle, take additional measurements for verification and then seek an explanation. The plastic filler and several coats of paint normally used to cover damage will produce thicker readings.

Best higher budget digital paint meter + review:
“I got it because my son and I were looking for a 69 Camaro that was reasonably priced. Found one that looked great and the seller (who had it painted) said the body was straight underneath. Found places on the car where there was so much filler the meter wouldn’t even get a reading! So for us, it paid for itself in one use! Not sure how the accuracy compares to much more expensive setups, but for someone like my son and I looking at used cars, it’s invaluable!”


The car coating thickness gauge can prevent expensive and unplanned body painting expenses. For inspectors, the thickness gauge can prevent lawsuits and preserve future business. Inarguably, the cost of the paint thickness meter is relatively low compared with what is at stake.

The used car dealer, insurance adjusters, painters, and body shops, among others, will need the thickness gauge to help them make the right business decisions.