testo 645 - Humidity/temperature measuring instrument

Order-Nr.  0560 6450

  • High-precision humidity measurement up to ± 1% RH

  • Internal reading memory (3,000 readings)

  • Convenient data evaluation via optional PC software

  • Possibility of attaching a really wide range of optional probes thanks to a large accessory portfolio

The testo 645 humidity/temperature measuring instrument automatically indicates the measurement parameters of relative humidity, absolute humidity, dew point, degree of humidity, enthalpy and temperature at the touch of a button.

This meter uses a sensor to start up.

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AED 2 361.00
excl. VAT

Product Description

The testo 645 high-precision humidity and temperature measuring instrument offers two probe inputs for attaching a comprehensive range of probes:
  • Channel 1: temperature probe, type K/J/S, NTC
  • Channel 2: humidity/temperature probe or Pt 100 temperature probe

At the touch of a button, the thermohygrometer automatically indicates the measurement parameters of temperature, relative humidity, dew point, pressure dew point, absolute humidity, degree of humidity and enthalpy, along with min., max. and mean values, as well as the last measured value. Convenient evaluation of the measurement data is possible using the optional PC software. Measurement data can also be printed out directly at the measuring location via the optional testo fast printer.

Areas of application of the testo 645 humidity/temperature measuring instrument

  • Monitoring of temperature and humidity values in production, storage and server rooms, museums, archives, cold stores, containers and display cases
  • Location of mould formation in residential or other buildings 


Delivery Scope

testo 645 humidity/temperature measuring instrument, including battery.
Temperature - Pt100

Measuring range

-200 to +800 °C


±0.1 % of mv (200.1 to 800 °C)

±0.2 °C (-200 to 200 °C)


0.1 °C

Temperature - NTC

Measuring range

-50 to +150 °C


0.1 °C

Temperature - TC Type K (NiCr-Ni)

Measuring range

-200 to +1370 °C


±0.5 % of mv (-200 to -60.1 °C)

±0.5 % of mv (+60.1 to +1370 °C)

±0.3 °C (-60 to +60 °C)


0.1 °C

Temperature - TC Type J (Fe-CuNi)

Measuring range

-40 to +750 °C


±0.5 % of mv (-200 to -60.1 °C)

±0.5 % of mv (+60.1 to +750 °C)

±0.3 °C (-60 to +60 °C)


0.1 °C

Temperature - TC Type S (Pt10Rh-Pt)

Measuring range

-50 to +1700 °C

Humidity - Capacitive

Measuring range

0 to 100 %RH


see probe data


0.1 %RH (-50 to +150 °C)

General technical data


215 x 68 x 47 mm

Operating temperature

0 to +50 °C

Product-/housing material


Number of channels


Battery type

9V block battery

Battery life

45 h

Battery feature

The hour times are reduced by a factor of 5 if a 9V rech. battery is used

Display type

LCD (Liquid Crystal Display)

Display size

4 lines

Storage temperature

-20 to +70 °C


255 g

Accessories: Humidity probes

Extension cable

Order Number: 0409 0063

AED 383.00
excl. VAT
Connection cable

Order Number: 0430 0143

AED 194.00
excl. VAT

Humidity probes

Humidity/temperature probe

Order Number: 0636 9742

AED 1 656.00
excl. VAT

Pt100 temperature probes

AED 1 449.00
excl. VAT

Printer and accessories

testo fast printer IRDA

Order Number: 0554 0549

AED 860.00
excl. VAT
AED 95.00
excl. VAT

Software and Accessories

RS232 cable

Order Number: 0409 0178

AED 254.00
excl. VAT

Transport and Protection