ST642 (Discontinued – see ST633)
General-purpose handheld infrared thermometer with Type K thermocouple input
Alternative Product:ST633


  • Low-cost, temperature gun-style infrared thermometer
  • Temperature range: -35°C to 550°C
  • Laser sighting with on/off switch
  • Adjustable emissivity setting for a variety of non-metal materials
  • Backlit display with audible alarms
  • Type K thermocouple input
  • Not designed or approved for fever detection


Emissivity Setting Adjustable 0.1 to 1.0
Type K Thermocouple Input YES
eSmart Emissivity Correction YES
Audible Alarm YES
Colour Changing Display for Alarm YES
°C/°F Switchable YES
Display Backlight YES
Laser Sight, Switchable YES
Max, Min, Avg, ΔT YES
Carrying Case Included YES
Tripod Mounting Thread YES
10 Point Memory NO (see ST633)

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)
180 x 130 x 40 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.
Model Description Price
ST642 Handheld infrared thermometer with laser sighting, adjustable emissivity setting and Type K thermocouple input Contact Calex