Low-cost handheld pocket infrared thermometer


  • Low-cost, gun-style infrared thermometer
  • Temperature range: -35°C to 630°C
  • Laser sighting with on/off switch
  • Selectable emissivity setting, ideal for use on rubber, wood, asphalt, plastics, painted surfaces, organic materials and many more
  • Backlit display
  • Audible alarms
  • Not designed or approved for fever detection


Emissivity Setting Selectable 0.95, 0.7, 0.3
Type K Thermocouple Input NO (see ST642)
eSmart Emissivity Correction NO (see ST642)
Tripod Mounting Thread NO (see ST642)
Colour Changing Display for Alarm NO (see ST642)
Audible Alarm YES
°C/°F Switchable YES
Display Backlight YES
Laser Sight, Switchable YES
Max, Min, Avg, ΔT YES
Carrying Case Included YES
10 Point Memory YES

General Specifications

Field of View
Temperature Range
-32°C to 535°C (-25°F to 999°F)
±3°C (±5°F) from -32°C to -20°C (-25°F to -4°F)
±2°C (±3°F) from -20°C to 100°C (-4°F to 212°F)
±2% above 100°C (212°F)
Spectral Range
5 to 14 μm
±1°C (±2°F)
0.1°C (0.1°F)
Response Time
500 ms
Operating Temperature
0°C to 50°C (32°F to 122°F), 10% to 90% RH
Power Off
Automatic after approximately 7 seconds
LCD with backlighting
Battery Type
9 V, PP3 (not supplied)
156 x 100 x 32 mm
195 g

Field of View Diagrams

Please note: The given measured spot size contains 90% of the energy detected by the sensor. We normally recommend the target is at least twice as large as the given measured spot for maximum accuracy. The thermometer may be used at longer distances than the above diagram shows, with a proportionally larger measured spot.

The pocket-sized ST633 is ideal for checking the temperatures of products and equipment in industrial processes.

Most non-metal materials can be measured with one of the ST633’s selectable emissivity settings. An emissivity setting of 0.95 suits painted surfaces, paper, asphalt, most textiles, rubber, resin composites, food, organic materials and many more.

Partially reflective surfaces can be measured with the emissivity settings of 0.7 and 0.3.

On metal surfaces, a measurable area should be painted or coated with a non-reflective non-metal material before taking measurements.

The ST633 unit’s 10-point memory makes it easy to perform routine daily walk-around temperature checks without carrying pen and paper.

Model Description Price
ST633 Handheld infrared thermometer with laser sighting, selectable emissivity setting, display, audible alarm, 10-point memory and soft carry case Contact Calex