Testo 635-1 Humidity/Temperature Meter

  • Takes up to two conventional probes and three radio probes (module required)
  • Measure temperature, humidity, dew point, absolute pressure and more
  • Large digital screen can display two measurement parameters at once
More Info
Typically ships in 2-4 working days

Testo 635-1 Humidity/Temperature Meter

The Testo 635-1 Humidity/Temperature Meter is a useful multifunction air quality meter that can work with up to two conventional probes or three radio probes at once (probes not included). The meter can take inputs from temperature, humidity, equilibrium moisture, absolute pressure and U-value probes across large ranges with high precision. Wireless probes only work with the optional radio module that can be retrofitted at any time and can communicate with the meter over a range of 20m.

The large backlit screen on the Testo 635-1 can show two parameters at the same time and the meter is capable of calculating the dew point temperature using air temperature and humidity calculations. It can show minimum, maximum and average values as well as the distance to dew point and it has a data hold function for keeping a reading on screen.

Operating the Testo 635-1 is surprisingly easy thanks to the push-button interface and it can work with an optional Testo fast printer to create cyclic hard copies of test results. An IP54 ingress protection rating means that the Testo 635-1 can stand up to the challenges of field use and it has a 200-hour battery life.

Testo part number: 0560 6351

Key Features

  • Up to two conventional probes
  • Up to three radio probes (with module)
  • Temperature, humidity, dew point and more
  • IP54 ingress protection rating
  • Large digital screen
  • Simultaneous parameter display

What's In The Box?

  • Testo 635-1 Temperature/Humidity Meter
  • Battery
  • Calibration protocol
  • Instructions for Testo 635-1

Type K Thermometer Input

  • Measuring range: -200˚C to 1370˚C
  • Accuracy: ±0.2˚C
  • Resolution: 0.1˚C

NTC Temperature Input

  • Measuring range: -40˚C to 150˚C
  • Accuracy: ±0.3˚C
  • Resolution: 0.1˚C


  • Measuring range: 0 to 100% RH
  • Accuracy: See probe data
  • Resolution: 0.1% RH

Absolute pressure

  • Measuring range: 0 to 2000hPa
  • Accuracy: See probe data
  • Resolution: 0.1hPa

General technical data

  • Operating temperature: -20 to +50 °C 
  • Storage temperature: -30 to +70 °C 
  • Battery type: Alkali manganese, mignon, Type AA 
  • Battery life: 200 h 
  • Dimensions: 220 x 74 x 46 mm 
  • Weight: 428 g 
  • Housing material: ABS/TPE/Metal