testo 405 - Pocket-sized thermal anemometer

Order-Nr.  0560 4053

  • Volume flow calculation of up to 99,990 m3/h

  • Easily read data at any angle with rotating display

  • Telescopic handle up to 300 mm

  • Ideal for measurements in ducts

Use the testo 405 thermal anemometer to measure air velocity, volumetric flow, and air temperature. It is suitable for carrying out quick check measurements in ventilation ducts, and for measuring the air velocity in rooms, such as at drafty windows.

Product Description

If, in your capacity as an HVAC engineer, you carry out fast check measurements in ventilation ducts or in rooms, then the testo 405 thermal anemometer is a must-have. The anemometer features a permanently mounted telescope and enables you to measure air flow, volumetric flow, and air temperature. The measuring range for flow is from 0 to 10 m/s, and volumetric flows are calculated up to 99,990 m3/h.
The extendible telescope (up to 300 mm) makes the thermal anemometer particularly suitable for flow measurements in ventilation ducts. The illuminated display can be swivelled into various positions, ensuring that the readings can be read comfortably. The duct bracket (included in the delivery) offers key practical advantages. You can use this to optimally position the telescope in the ventilation duct and obtain precise measurement results.
Since the testo 405 thermal anemometer measures particularly accurately in the range between 0 and 2 m/s, you can also use it to measure the air velocity in rooms. Low air velocities, at drafty windows for example, are quickly located and accurately measured using the anemometer.
Integrated sensor protection: When you are not using the testo 405 thermal anemometer, the rotating protective cap protects the flow sensor from mechanical stress.


Delivery Scope

testo 405 thermal anemometer with permanently mounted telescope, including duct bracket, attachment clip, and batteries
Temperature - NTC

Measuring range

-4.0° to 122.0 °F / -20 to +50 °C


±0.9 °F / ±0.5 °C


0.1 °F / 0.1 °C

Velocity - Thermal anemometer

Measuring range

0 to 984 fpm (-4.0° to 32.0 °F) / 0 to 5 m/s (-20 to 0 °C)

0 to 1968 fpm (32.0° to 122.0 °F) / 0 to 10 m/s (0 to +50 °C)

0 to 58852 CFM / 0 to 99990 m³/h


±(19.7 fpm + 5 % of mv) (0 to 394 fpm) / ±(0.1 m/s + 5 % of mv) (0 to 2 m/s)

±(59.1 fpm + 5 % of mv) (Remaining Range) / ±(0.3 m/s + 5 % of mv) (Remaining Range)


2.00 fpm / 0.01 m/s

General technical data


19 x 2 x 1 in. / 490 x 37 x 36 mm

Operating temperature

32.0° to 122.0 °F / 0 to +50 °C


2 years

Battery type

3 x AAA

Battery life

Approx. 20 h

Display type


Length probe shaft

11.8 in. / 300 mm

Diameter probe shaft

0.6 in. / 16 mm

Diameter probe shaft tip

0.5 in. / 12 mm

Storage temperature

-4.0° to 158.0 °F / -20 to +70 °C


4 oz. (with batteries, without packaging) / 115 g (with batteries, without packaging)

Measurement of indoor air velocity

For workers to feel comfortable in their indoor working environments, "thermal comfort" has to prevail. The EN 13779 describes this as a state that prevails when people are satisfied with the air temperature, humidity, air movement and thermal radiation in a room, and require neither hotter, colder, nor drier or more humid indoor air.

The testo 405 is particularly well suited to measuring indoor flow velocity. Low air velocities, such as at draughty windows, can therefore be precisely located and measured extremely accurately.

Measurement in ventilation ducts

Observance of air flows in the ventilation duct is of utmost importance for the function of the ventilation and air conditioning system. If the air flows are smaller than intended, the removal of room loads (heating, cooling and substance loads) may not be ensured in certain circumstances. Therefore, the most accurate recording of air flows as possible is particularly important.

Our thermal anemometer testo 405 allows particularly cost-effective measurement of low air velocities. It enables the accurate and parallel measurement of air flow, volumetric flow and temperature. The extendible telescope allows measurement at a depth of up to 300 mm.

The display can be swivelled into various positions, enabling optimum measurement readout.