How To Measure Car Paint Depth Using a Paint Thickness Gauge


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measure car paint depth using paint thickness gauge, coating thickness gauge, paint thickness

Measuring car paint thickness is a very important step when you’re polishing or compounding cars. Today, I’ll show you how to measure car paint depth using a paint thickness gauge and what you should check when measuring the paint thickness. 

To check the paint thickness on your vehicle, lean the coating thickness gauge sensor to the surface of the panel you want to measure. When it finishes measuring (<1sec), it’ll show the result on the device’s display. 

In order to determine car paint thickness correctly, there are more things you should know than just leaning the device onto the paint. 

I want to show you all the details you should pay attention to, so make sure to spend few minutes and read the whole article. 

How Do Paint Thickness Gauges Work 

Digital paint thickness gauges work by measuring the distance between the body panel and the sensor on the device. That distance measured is the overall thickness of the paint (primer coat, base coat, and clear coat). 

Most paint thickness gauges can work on metal and aluminum car panels only. However, some more expensive and professional devices can measure the paint thickness even on plastic and carbon panels. 

Also, some highly professional paint depth gauges may tell you the exact thickness of each coating (primer, base, and clear coat). But they’re still too expensive for most people out there. There’s just no ROI to use them.

What Data Do They Show 

Most paint thickness gauges show one data only, but it can be shown in two different units:

  1. Microns (μm) – it’s 1/1000 of a millimeter. In my opinion, it’s the unit you should measure car paint thickness since it’s much more precise than the mills. 
  2. Mills – it’s 25.4 microns or 1/1000 of an inch. As you can see, microns are much more precise. (make sure not to think it’s a millimeter).

Also, some devices will show you the result without decimals, and some of them will show you even two decimals. I suggest you always buy a gauge that shows decimal numbers, especially if you want to measure the paint depth in mills. 

Today, most coating thickness gauges can save results and count the average measures, which can be exported to the computer or directly read from the device.

Honestly, the more features they have, the better. There are gauges with wifi or Bluetooth options so that you can read the data on your phone, gauges with external sensors, etc. 

If you don’t have a coating thickness gauge, but want to buy one, check out my article: Best Paint Thickness Gauges For Car Detailers (Under $150)

How To Measure Car Paint Depth 

Measuring car paint thickness is effortless, thanks to excellent coating thickness gauges. 

Steps For Measuring The Car Paint Thickness:

  1. Turn on the paint thickness gauge.
  2. Pick a unit – I prefer microns (μm) since they are more precise.
  3. Make sure it’s calibrated – when you buy the gauge, you’ll probably get some samples inside the box to check if the sensors are calibrated. It’s a piece or two of metals with some plastics of various thicknesses. 
  4. Lean the sensor to the car surface you want to measure and wait for results to be shown.
  5. Measure each panel a few times – make sure to make a few readings on every panel. Each measuring should be done on a different spot. That way, you can get some average paint depth.

Those are the most important steps you should take when measuring the car coating thickness. 

If you’re going to polish or compound the car, make sure that you get good enough results. That way, you’ll make sure that the clear coat is thick enough for safe polishing.

What Are Good Paint Depth Results

There’s no definitive answer to how thick paint should be on any vehicle. Each vehicle is different, even from the same manufacturers. However, there are some general rules you should follow. 

Most new cars will have a paint depth of around 100-150 microns or about 4-6 mills, depending on what unit you use to measure the thickness. 

ManufacturersAverage Paint Thickness
European Cars100 to 150 microns (μm) / 4 to 6 mills
USA Cars100 to 150 microns (μm) / 4 to 6 mills
Japanese Cars90 to 120 microns (μm) / 3.5 to 4,7 mills
Average Paint Thickness of Cars

As you can see, not all cars use the same paint depth standard. Also, you can expect more expensive cars to have thicker paint, while cheaper cars will often have thinner paint.

Mostly, a good paint result is anything that’s above 90 microns (3.14 mills). With that result, you’re probably safe to do a paint correction. Again, it depends on the type of the vehicle and its factory paint depth.

The best way to tell if there’s still enough clear coat is to measure the average, and then you’ll know what a good result of a specific part is good.

Related: 5 Common Auto Detailing Questions About Clear Coat (Answered)

For instance, if the average thickness is 120 microns (µm), and the hood is 80 microns, there’s probably not much clear coat left there, and you should be extremely careful if you’ll polish that car. Usually, the clear coat thickness varies between 40-50 microns (µm). 

3 Situations To Use Coating Thickness Gauges

car paint fillers, fixing car paint,

Here I’ll show you the three most common reasons why people use paint thickness gauges. 

1.Before Polishing and Compounding

Before you do a paint correction process, you should always check the paint depth and estimate the clear coat thickness. Of course, you can never tell 100% how thick is a clear coat, but paint gauges can help a lot with estimating that.

Polishing cars isn’t very hard. If you want to learn to polish, check my guide on how to properly polish your car using a machine polisher.

2. To Check Your Painting Job

When you’re painting a vehicle, it’s good to check the paint depth after you finish painting all the coats (primer, base, and clear). That way, you’ll know if you did a good or a bad job. It’s always best to get readings similar to the factory ones. 

When you do it few times on a few different panels, you’ll get a better feeling when painting the car, and you’ll know how many coats of paint or clear coat you should apply next time. 

If you’re a beginner, it’s a great way to learn about painting vehicles. You just spray some old spare parts and then check the results with the coating thickness gauge. 

I have found a fantastic course for beginners to learn how to spray paint any car. It’s called Learn Auto Body and Paint (check it now). 

3. When Buying a Used Car

When you’re buying a used car and you’re not sure if the car was re-painted or had some accidents, using paint thickness gauges can help you with that. 

One of the signs that the car was re-painted or has fillers is if there is a significant deviation in paint thickness of different car panels.

If you get incredibly high readings (250+ microns), it’s a sign that there are fillers beneath the paint, and that car probably had some crush, or the metals were rusty. If you get those readings, I advise you to check the VIN History of that vehicle, too (check it now). 

Frequently Asked Questions

Are paint thickness gauges expensive?

Luckily, with the expansion of the paint thickness gauges market, the prices went down. As always, there are more expensive and cheaper products. You can find a good gauge for around $100. The prices can go up to $1000 if you want professional tools. Check my recommended coating thickness gauges here.

I’m a car detailer. Do I need a coating thickness gauge?

Yes. You’ll need it sooner or later, especially if you’re polishing vehicles. It’s a great piece of equipment that can help you a lot.

Do extremely cheap coating thickness gauges work?

They’ll work, but I wouldn’t trust some device that costs $30. It’s just not enough money to get a reliable device.

Can I measure the paint thickness of the plastic panels?

With most middle-priced gauges, that won’t be possible. However, if you want to invest in a more professional device, you’ll be able to measure the thickness of plastic and carbon panels.

Can I measure the thickness of specific car paint coats?

If you want to check the exact thickness of specific car paint coats (e.g., clear coat), you’ll have to use expensive devices that have that option. Most paint thickness gauges don’t have that option.

Conclusion

As you can see, using paint thickness gauges to measure the car paint depth is extremely easy. Estimating the “good” paint depth will require a bit of experience, and you’ll achieve that with time. 

One important thing I need to tell you is that paint thickness gauges are HELPERS. You shouldn’t wholly lean on results only. What you see is much more important.

I think that I was thorough enough to explain the essential things about measuring the car paint thickness. I tried to make it as simple as possible, so you can easily understand everything. 

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