Guide · Paint-thickness gauges
AUTO BILD's 2021 paint-gauge test
AUTO BILD compared ten Fe/NFe paint gauges in 2021. What it did, what it found, and why one sample per model in an older German test is not a current ranking.
Short answer
AUTO BILD compared ten Fe/NFe paint gauges in 2021, on control foils and then on 22 professionally painted panels, using the Q-Nix 5500 as its reference device.[1] It found that some gauges strayed far from the reference: one NexPTG Professional sample by up to 118%, and three budget gauges with implausible values. It is one of the few independent comparisons, but it is a 2021 test of German-market models, one sample each, so read it as a warning to verify your own gauge rather than a current ranking.
How old is it?
The test page carries a price note dated 20 May 2021, so the test dates from 2021 even though the page is still online.[1] It appeared under AUTO BILD KLASSIK and covers gauges sold in Germany at the time. Models, firmware and prices have changed since. Some articles describe it as a recent test; it is not.
What AUTO BILD did
- Ten gauges, all with Fe and NFe capability.[1]
- Step one: plastic control foils from 48 to 1006 µm.[1]
- Step two: 22 panels painted by a professional painter, 3 aluminum and the rest steel.[1]
- Reference: the Q-Nix 5500, chosen because it was the most precise on the control foils. It is not an accredited laboratory master.[1]
- Method: each reading was repeated until three identical values appeared.[1]
What it found
| Finding | What it covers | What it does not show |
|---|---|---|
| A NexPTG Professional sample deviated by up to 118% from the reference on the test panels, mostly reading lower, and ranked 10th of 10[1] | One unit of one model in 2021 | That every NexPTG gauge, or current NexPTG models, read this way |
| Three near-identical budget gauges (BGS, KS-Tools, Busching) gave some implausible values, including one reading above 2000 µm on a gauge rated only to 1000 µm[1] | Three specific German-market models | That all budget gauges are unreliable |
| Tin-filled repairs on a steel body can only be found with a gauge that also has NFe capability[1] | A practical point about gauge type | Which models find them most reliably |
A deviation measured against a reference device is not the same as a deviation from true thickness. The reference was the most precise of the group on foils, not a certified standard. That does not undo the findings, but it is one more reason not to over-read the exact percentages.
What AUTO BILD says about reading results
- Factory vs repaint figures: factory finishes usually 80-150 µm and manual repaints typically above 200 µm, which AUTO BILD itself calls only rough guidance, adding that factories sometimes repaint.[1] These are not thresholds; see normal car paint thickness.
- Mirrored spots: a much higher reading on one side of the car than at the same spot on the other side indicates a repair with repaint.[1]
- Experience: interpreting readings needs experience with vehicle generations and paint systems.[1]
Our line is more cautious: a gauge shows thickness, not the cause. A difference is a reason to look closer, not proof.
Other comparisons you will find
Forum comparisons exist. On Auto Geek Online, one member compared two inexpensive gauges (Nicety CM8801FN and AGPtek EM2271) and reported handling and probe-design differences that affected how consistently readings could be taken.[2] That is one user's experience with older models and supplied shims, useful for what to look out for, not a measurement study.
We found no newer independent accuracy test of paint gauges sold in the US or Canada.
What to take from it
- Spec sheets are claims. A gauge can display confident numbers and still be well off. See accuracy vs resolution.
- Verify your own unit. Zero on bare metal and check shims before each inspection: how to calibrate and verify a paint gauge.
- Get NFe as well as Fe. It covers aluminum panels and, per AUTO BILD, tin-filled repairs: magnetic vs eddy-current gauges.
- Distrust impossible numbers. A reading above the gauge's rated range is a fault, not a measurement.
Next
Questions
Is the AUTO BILD paint gauge test recent?
No. The page dates its prices to 20 May 2021, so it is a 2021 test of gauges sold in Germany at the time, even though the page is still online.[1]
Does the test show NexPTG gauges are inaccurate?
It shows that one NexPTG Professional sample deviated by up to 118% from AUTO BILD's reference device in 2021. That is one unit of one model, not every NexPTG gauge or current models.[1]
Are cheap paint gauges unreliable?
AUTO BILD found implausible values from three specific budget models, including one reading above 2000 µm on a gauge rated to 1000 µm. That is a warning to verify any gauge, not a rule for all budget gauges.[1]
What did AUTO BILD use as its reference?
The Q-Nix 5500, because it was the most precise of the group on plastic control foils from 48 to 1006 µm. It was not an accredited laboratory master.[1]
Does AUTO BILD say 200 µm means repainted?
It gives factory finishes as usually 80-150 µm and manual repaints as typically above 200 µm, but calls these only rough guidance and notes that factories sometimes repaint. It is not a threshold.[1]