Which paint thickness gauge should I choose for a pre-purchase inspection?

For most cases, a portable electromagnetic Fe/Al gauge is sufficient. It is more accurate than simple magnetic tools and cheaper than ultrasonic devices. If you must measure on plastic, choose an ultrasonic gauge.

What is a normal factory paint thickness?

Most commonly 90–160 μm on steel; aluminium is usually thinner. Local variations up to about 180–200 μm are acceptable. Readings of 300–500 μm indicate filler; 700+ μm point to major repairs.

What if the gauge shows filler on structural elements?

The car most likely suffered a serious accident. We recommend walking away or, at minimum, doing an in-depth geometry check and negotiating a large discount.

Paint Thickness Gauge: Where to Look for Repairs and How to Read the Numbers

When buying a used car, you don’t want one with heavy accident history. Bodywork can be done so well that the car looks brand-new. The reliable way to know is to measure the paint with a thickness gauge. We use it every day across Germany (especially Berlin & Brandenburg) to give clients a transparent history. Listings often say “unfallfrei” (“accident-free”), but definitions vary: small repairs may “not count”, and less honest sellers omit crashes. Measuring the paint yourself or hiring experts is the most reliable path.

Why a paint thickness gauge matters

A paint gauge measures coating thickness. Types include magnetic (simple, imprecise), electromagnetic (more accurate; works on steel and aluminium) and ultrasonic (more expensive; can read on plastics). For car buying, a compact electromagnetic Fe/Al gauge is typically enough.

From factory, paint is even. Most cars show about 90–160 μm (local spots up to ~180–200 μm). Considerably higher numbers mean a respray; multiples often indicate body filler. A respray alone isn’t a deal-breaker (scratches, hail). But filler and a “layer cake” on structural elements are red flags—check geometry and history. ECU/airbag scans also help.

From practice: a flawless-looking car showed ~800 μm on the roof—thick filler under the paint. Later we learned it had rolled over.

Where and how to measure

Calibrate the gauge using the reference foils per the manual—otherwise readings won’t be trustworthy.
Measure each panel at least in 5 spots (corners + center) and take 2–3 readings per spot—use the average.
Probe perpendicular on a clean surface: tilt/dirt inflates numbers.
Don’t skip the roof. Factory there is often 70–120 μm; outliers suggest hail/rollover.
Check pillars and sills. Critical for safety—repairs here matter most.
Materials. Aluminium is usually thinner; modern gauges show Fe/Al. If the bonnet “suddenly reads Fe” on an aluminium car—likely replaced.
Plastics. EM gauges don’t read plastic; ultrasonic is required. Cosmetic plastic work is less critical.

Decoding the readings

~200+ μm: likely respray (incl. clear coat). Inspect closely.
300–500 μm: high chance of filler—repairs done. On structural parts, it’s a serious risk.
700–900 μm: very thick “layer cake”, used to correct major deformation. Future cracking/peeling possible.
1000+ μm: almost certain heavy crash damage. Best avoided.

Judge the whole car: a single local respray is a bargaining point; a “chain” of high values on adjacent panels (fender+door+pillar) hints at a major hit.

Other repair clues

Colour/finish mismatch: tone, gloss, orange-peel, runs.
Disassembly marks: chipped paint on wing bolts, door hinges, bonnet latch.
Uneven gaps: asymmetry suggests pulled chassis.
Glass & lights: year codes should match the car.
Rails & floor: fresh seams/sealant, irregular corrosion—signs of repairs.

The gauge is a tool, not a verdict. An expert correlates readings with visual and legal checks to give a confident recommendation.

Buying a car in Germany? We’ll check bodywork and history for you

Our Sicher-Check team works in Berlin, Potsdam and across Germany. You get:

🔎 Document & history check (VIN reports, damage photos, mileage).
🧲 Paint measurements with a 5-point-per-panel method.
💻 OBD diagnostics, fault scan, test drive.
📝 A written “buy / don’t buy” verdict + bargaining arguments.
💬 English / German / Polish / Ukrainian.
💶 Transparent prices and a request form online.

Book now All services Prices / packages Online request

Reference paint thickness: steel vs aluminium

Values are averages and depend on model/plant. Compare panels on the same car and look for “chains” of anomalies.

Material	Panel	Factory thickness, μm	Acceptable variation	Be cautious if	Comment
Steel (Fe)	Fender/door/bonnet	90–160	up to ~180–200	>220 — likely respray; >300 — filler	Compare left/right sides and adjacent panels
Steel (Fe)	Roof	70–120	up to ~150–160	>180 — hail/repair signs; >300 — filler	Roof anomalies often point to rollover
Aluminium (Al)	Bonnet/fender/door	60–110	up to ~130–150	>180 — respray; >280 — filler	If the gauge reads “Fe” on an aluminium part — likely replaced
—	Plastic (bumpers etc.)	—	—	EM gauge won’t read	Ultrasonic required; plastic cosmetics are less critical

Note: a single local respray = room to negotiate. A “chain” of high values (fender+door+pillar) = evidence of a major hit.

Measuring map: five spots per panel — four corners and the center; must-check zones: pillars, sills, roof — Method tip: at least 5 spots per panel (corners + center), take 2–3 readings per spot. Always measure pillars, sills and the roof.

FAQ — frequently asked questions

Which paint gauge should I buy for pre-purchase checks?

An electromagnetic Fe/Al gauge covers most needs. If you must measure plastics, choose an ultrasonic gauge.

What’s a normal factory paint thickness?

Often 90–160 μm on steel with local spots up to ~180–200 μm. Aluminium is usually thinner. Readings of 300–500 μm suggest filler.

What if I see filler on pillars and sills?

It’s a marker of serious impact. We recommend a deeper geometry check; in most cases, walk away.