A thickness gauge answers a different question depending on its type. A coating gauge reads the layer on top of metal, such as a finish or plating. An ultrasonic gauge measures the wall of a solid part when you can reach only one side. Ranges, units and memory vary widely.
The six gauges below split three and three between those types. All figures come from each product’s listing page and are the makers’ own claims. We have not used these gauges ourselves. Read the maker’s manual for the surfaces and materials each one supports.
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What to Look For
| Feature | Why it matters |
|---|---|
| Type | Coating gauges read layers on metal; ultrasonic gauges read solid material |
| Range | Microns or mils for coatings, inches or mm for solid parts |
| Substrate | Some gauges detect steel or aluminum automatically |
| Memory and export | Stored readings and USB help with records |
| Power | Batteries, or none for a purely magnetic gauge |
Specs at a Glance
| Gauge | Type and range | Stated resolution or accuracy (maker) | Notes |
|---|---|---|---|
| CM-208FN | Coating; 0 to 2000 microns (0 to 78 mils) | 0.001 mil resolution up to 3.93 mils | Auto steel and aluminum detection; USB data export |
| CM-205FN | Coating; 0 to 1500 microns (0 to 59.1 mils) | 0.1 micron resolution; plus or minus (3% + 2 microns) | Backlit LCD; auto detection; set up at the factory |
| PosiTest G | Coating; 0 to 200 microns | Plus or minus 1 micron to 20; 5% above 20 | Magnet-based, no batteries; non-magnetic coatings on steel |
| Triplett UTG300 | Ultrasonic; 0.04 to 11.81 in | Not read | Stores 300 records; min, max and average; high and low alarms |
| Starrett ultrasonic | Ultrasonic; 0.040 to 12.0 in | Plus or minus (0.5% + 0.001 in) | 2000 readings in 20 groups; about 100 hours on 2 AA |
| Industrial-882 | Ultrasonic; 0.039 to 8.858 in | Not read | Color LCD; auto calibration; echo-based, one side access |
The 6 Best Thickness Gauges
1. CM-208FN Coating Thickness Gauge
A coating gauge with a built-in ruby-tip probe, a range of 0 to 2000 microns (0 to 78 mils) and automatic detection of steel or aluminum underneath. The listing states resolution of 0.001 mil from 0 to 3.93 mils, coarser steps above that, and USB data export. It is described for vehicle and field inspection.
Suits: checking coating layers on steel or aluminum. Strengths: fine resolution and USB export. Weaknesses: accuracy figures were not read in the text. Skip it if you need to measure solid wall thickness.
View CM-208FN Coating Thickness Gauge 0-2000 micron on Amazon
2. CM-205FN Coating Thickness Gauge
A handheld coating gauge, 4.33 by 2.09 by 0.91 inches, covering 0 to 1500 microns (0 to 59.1 mils) with 0.1 micron resolution and a stated plus or minus (3% + 2 microns). It detects the base metal automatically, has a backlit LCD and is described as set up at the factory.
Suits: a simple backlit coating gauge. Strengths: a stated accuracy formula and auto detection. Weaknesses: a smaller range than the CM-208FN. Skip it if you need data export.
View CM-205FN Coating Thickness Gauge 0-1500 micron on Amazon
3. DeFelsko PosiTest G Coating Gage
A magnet-based gage that needs no batteries. It measures non-magnetic coatings from 0 to 200 microns on steel, with a stated plus or minus 1 micron up to 20 microns and 5 percent above. The maker lists a carbide probe, a leather case and a calibration certificate.
Suits: thin coatings on steel without batteries. Strengths: a small, simple design with stated accuracy. Weaknesses: a 200 micron range and steel only. Skip it if you need a digital display or aluminum.
View DeFelsko PosiTest G Coating Gage 0-200 micron on Amazon
4. Triplett UTG300 Ultrasonic Thickness Gauge
An ultrasonic gauge covering 0.04 to 11.81 inches (1 to 300 mm) in steel, stainless steel, brass, copper, iron, lead, glass and more. It has a 2.4 inch display with metric or inch readout, can store 300 records, shows min, max and average, and offers high and low alarms.
Suits: solid parts with one-sided access. Strengths: 300 records and alarms. Weaknesses: an accuracy figure was not read. Skip it if you only measure surface coatings.
View Triplett UTG300 Ultrasonic Thickness Gauge on Amazon
5. Starrett Ultrasonic Thickness Tester
An ultrasonic tester covering 0.040 to 12.0 inches with a stated plus or minus (0.5% of thickness + 0.001 inch). It stores up to 2000 readings in 20 groups and runs about 100 hours on two AA cells, with inch and mm readout after calibration. The listed size (17.2 by 10.8 by 4.1 inches) does not fit its 16 ounce weight, so treat that size as unclear.
Suits: record keeping across groups. Strengths: large memory and a stated accuracy formula. Weaknesses: a conflicting size entry. Skip it if you want a color display.
View Starrett Ultrasonic Thickness Tester 0.040-12 in on Amazon
6. Industrial-882 Ultrasonic Thickness Gauge
A handheld ultrasonic gauge, 7.87 by 4.72 by 1.97 inches, with a range of 0.039 to 8.858 inches (1 to 225 mm), a color LCD and auto calibration. The listing says it works from one side by timing the echo and mentions steel, pipes and tanks.
Suits: a color display. Strengths: a color LCD and compact size. Weaknesses: a shorter range than the Triplett or Starrett. Skip it if you need parts thicker than 8.858 inches.
View Industrial-882 Ultrasonic Thickness Gauge 1-225 mm on Amazon
Care and Setup
- Read the maker’s manual for supported materials and surfaces.
- Keep probes clean and store gauges in their cases.
- Use the couplant the maker names for ultrasonic gauges.
- Replace batteries when the low battery indicator appears.
Mistakes to Avoid
- Using a coating gauge for solid wall thickness, or the reverse.
- Comparing a micron range with an inch range without converting.
- Ignoring which base metals a gauge supports.
- Skipping the manual.
Thickness Gauge FAQ
What is the difference between coating and ultrasonic gauges?
Coating gauges read a layer on top of metal. Ultrasonic gauges read the thickness of a solid part from one side.
Do these gauges need calibration?
Some are described as ready from the factory and others offer auto or user setup steps. Follow each maker’s manual.
The Short Version
For fine coating resolution and USB, the CM-208FN. For a backlit coating gauge, the CM-205FN. For no batteries, the PosiTest G. For stored records and alarms, the Triplett. For large memory, the Starrett. For a color screen, the Industrial-882.
