testo 440 dP - Air velocity and IAQ measuring instrument with differential pressure sensor

Order-Nr.  0560 4402

  • A measuring instrument for all climate-related parameters

  • Includes a differential pressure sensor: for Pitot tube measurement and monitoring filters

  • Extendible with a wide range of probes

  • Wireless measurement with Bluetooth probes

  • USB interface for exporting measurement reports as CSV files

  • Intuitive measurement menus

Precise, reliable measurement of all air velocity and IAQ parameters with just one measuring instrument – the testo 440 dP. This multifunction measuring instrument is intuitive and easy to use, thanks to its integrated differential pressure sensor and clearly structured measurement menus. Adjusting air conditioning and ventilation systems, monitoring air quality, and carrying out comfort level measurements are all possible without the hassle of juggling different devices and tools. Enjoy the versatility of using your choice of high quality digital probes with just one measuring instrument.


A measuring instrument for all climate-related parameters


Product Description

Use the testo 440 dP air velocity and IAQ measuring instrument in combination with high quality probes to measure and store all air velocity and IAQ parameters. Up to 3 probes can be connected simultaneously – a Bluetooth probe, a wired probe, and a temperature probe with a type K thermocouple connector (probes sold separately). Automatic probe detection and clearly structured measurement menus guarantee simple operation and will make your day-to-day work easier.
The testo 440 dP comes with an integrated differential pressure sensor. This enables filter and fan measurements, as well as pitot tube and K factor measurements (pitot tube sold separately).


Measure in no time with the testo 440 dP multifunction measuring instrument

Carry out your measurements quickly and easily. This multifunction instrument automatically detects each connected probe, which means you won't need to manually reset measurement parameters when changing probes. Clearly structured measurement menus for measuring the volume flow in ducts and at outlets, funnel measurement, determining volume flow via differential pressure and K factor, measuring the degree of turbulence, determining heating/cooling output, mold detection, and long-term measurement provide you with the optimal support for quick and efficient work.


A wireless space saver: More applications, less equipment

Endlessly versatile – the universal probe handle can be connected to all probe heads, so you can measure everything you need, while saving money and space.

The Bluetooth probe handle makes it more convenient to carry out your measurements, and guarantees less cable clutter in your case. It makes it possible to carry out measurements without any bothersome cable connections, and it transfers readings up to a distance of 65 feet. If using a wireless connection is not possible, use the cable probe handle as a practical alternative.


Practical measurement data management

The testo 440 dP stores up to 7,500 measurement protocols, which can be read via USB port and further processed as a CSV file on your computer (e.g. with Excel). With the testo Bluetooth / IrDA printer (sold separately), you have the ability to produce a printed report of measurement data directly on site.


Intelligent calibration concept for maximum precision

You can rely on the accuracy of your measurement results with our digital probes, because the testo 440 dP makes measurement uncertainty a thing of the past. You only need to send the probes in for calibration, meaning the multifunction instrument can remain in continuous use with a variety of interchangeable probes.



Advantages of measuring with the testo 440 dP air velocity and IAQ measuring instrument

Precise and reliable in ducts and at air outlets
  • Large range of connectable probes: Hot wire and vane probe (Ø 0.6") for measurements in ducts, large vane probes (Ø 4") for measurements at air/ceiling outlets
  • Calculate volume flow quickly: In the measurement menu, simply configure the dimensions and geometry of the duct cross-section and see the volume flow displayed straight away
  • Easy to carry out measurements in larger ducts, due to the extendable telescope on the hot wire and vane probes (Ø 0.6"), up to a total length of about 6.5 feet
  • Carry out measurements at air/ceiling outlets effortlessly, without using a ladder – fit the vane probe (Ø 4") with the extendable telescope and 90° angle (both sold separately)
  • Use the vane probes in conjunction with the testovent measurement funnels and flow straighteners to test incoming / outgoing air at plate outlets, ventilation grills, and swirl outlets
  • Practical Bluetooth interface: Use the air velocity probes to measure without having to deal with any bothersome cables, operate the measuring instrument by pressing the button on the handle of the probe, e.g. to start or stop a timed mean calculation
  • Use the practical rear magnets to securely attach the multifunction measuring instrument to metal surfaces (e.g. ventilation ducts)
Long-term monitoring of indoor air quality
  • The right probe for your requirements: Probes for CO2, CO, and air temperature and humidity are available as wired or Bluetooth variants
  • Easy to use: Enter the measurement period and interval for long-term measurement, and track it over the course of the day
  • Internal memory for up to 7,500 measurement protocols
Turbulence measurement in accordance with EN ISO 7730 / ASHRAE 55
  • Attain a high level of accuracy, even at low air velocities, with a turbulence probe
  • Automatic calculation of draft risk and degree of turbulence in accordance with EN ISO 7730 / ASHRAE 55
  • For convenient measurements at varying heights, we recommend using our measuring tripod for comfort level measurement – this makes it easy to position turbulence probes in compliance with testing standards
Wide range of probes for laboratories and cleanrooms
  • Fume hood probe for high precision air velocity measurements
  • Thanks to its low startup speed of 0.1 m/s, the available vane probe (Ø 4") is ideal for laminar flow measurements in cleanrooms, available as a wired or Bluetooth variant
  • High precision temperature / humidity probe (0636 9771 or 0636 9772) with an accuracy of ±0.6% RH + 0.7% of m.v. in the 0-90% RH range for measuring the humidity in cleanrooms

Delivery Scope

testo 440 dP air velocity and IAQ measuring instrument with integrated differential pressure sensor, connection hose, 3 AA batteries, USB cable, and calibration protocol

Technical Data

Temperature - NTC

Measuring range

-40.0° to 302.0 °F / -40 to +150 °C


±0.7 °F (-40° to -13.2 °F) / ±0.4 °C (-40 to -25.1 °C)

±0.5 °F (-13° to 166.8 °F) / ±0.3 °C (-25 to +74.9 °C)

±0.7 °F (167° to 211.8 °F) / ±0.4 °C (+75 to +99.9 °C)

±0.5 % of mv (Remaining Range)


0 °F / 0.1 °C

Temperature - Type K TC

Measuring range

-328.0° to 2498.0 °F / -200 to +1370 °C


±(0.5 °F + 0.3 % of mv) / ±(0.3 °C + 0.3 % of mv)


0 °F / 0.1 °C

Differential pressure (internal sensor) - Piezoresistive

Measuring range

-60 to +60 InH₂O / -150 to +150 hPa


±0.02 InH₂O (0 to 0.40 InH₂O) / ±0.05 hPa (0 to 1.00 hPa)

±0.1 InH₂O + 1.5 % of mv / ±0.2 hPa + 1.5 % of mv

(0.40 to +60 InH₂O) / (1.01 to +150 hPa)


0.00 InH₂O / 0.01 hPa

General technical data


8.8 oz. / 250 g


6.1 x 2.6 x 1.3 in. / 154 x 65 x 32 mm

Operating temperature

-4.0° to 122.0 °F / -20 to +50 °C

Connectable probes

1 x digital probe with cable or 1 x Temperature NTC TUC, 1 x digital Bluetooth probe or testo Smart Probe, 1 x differential pressure (internal), 1 x Temperature TC Type K

Product colour


Battery type

3 x AA 1.5 V

Battery life

12 h (typically vane measurement)


Bluetooth®; USB

Storage temperature

-4 to +122 °F / -20 to +50 °C


Comfort probes

Globe probe Ø 5.9"

Order Number: 0602 0743

Humidity probes

Order Number: 0560 2605 03

Pitot tubes

Pitot tube, stainless steel, 3.3 ft

Order Number: 0635 2345

Pitot tube; (length: 360mm)

Order Number: 0635 2043

Pitot tube; (length: 500mm)

Order Number: 0635 2143

Pitot tube; (length: 1000mm)

Order Number: 0635 2243

Pressure Probe

Order Number: 0560 2549 03

Temperature probes

$ 136.00
excl. tax
Immersion tip, flexible

Order Number: 0602 5793

Order Number: 0560 2115 03

Velocity Probe

$ 155.00
excl. tax
$ 915.00
excl. tax
$ 702.00
excl. tax



USB power supply including cable

Order Number: 0554 1105

$ 577.00
excl. tax

Additional Accessories

Flow straightener testovent 417

Order Number: 0554 4172

Transport Case

$ 113.00
excl. tax
$ 297.00
excl. tax


Long-term monitoring of indoor air quality

Poor indoor air quality due to excessive concentrations of CO2 can cause tiredness, lack of concentration and even illness. With its menu for recording readings, the testo 440 air velocity and IAQ measuring instrument is ideal for monitoring the indoor air quality. Enter the measurement time and the measuring cycle – and, for example, track the change in CO2 concentration or humidity and temperature values over the course of the day. Simply choose between probes with Bluetooth or fixed cable for CO2, CO or humidity (please order probes separately).

Convenience and maximum flexibility for duct and outlet measurements

With our large range of air velocity probes (please order separately), you can carry out simple and convenient measurements even at locations that are difficult to access in ventilation ducts or at air outlets:
you will even find it easy to carry out measurements in particularly large ducts. This is because the extendable telescope on the hot wire and vane probe (Ø 16 mm) with universal handle can be further extended using the telescope extension – enabling you to attain a total length of 2 metres.
Carry out measurements at air/ceiling outlets effortlessly and without using a ladder. Fit your vane probe (Ø 100 mm) with the telescope with 90° angle and, if necessary, with the telescope extension (both can be ordered separately).
Greater freedom thanks to Bluetooth: the air velocity probes with Bluetooth have no inconvenient cable connection to the measuring instrument, and they transmit readings up to a distance of 20 m. Press the button on the probe to operate the measuring instrument – for example, to start and stop a series of measurements (timed mean calculation).
Attach the testo 440 air velocity and IAQ measuring instrument to metal surfaces (e.g. ducts) easily using the practical magnets.
Benefit from fast calculation of the volume flow: in the “volume flow” measurement menu of the multifunction measuring instrument, configure the dimensions and geometry of the duct cross-section – the measuring instrument shows you the volume flow straight away.

Turbulence measurement in accordance with EN ISO 7730 / ASHRAE 55

Determine the degree of turbulence and the draught risk in the workplace: draught restricts the comfort level and is the most common cause of complaints about the indoor climate. The turbulence probe (please order separately) measures air velocity and air temperature, and automatically calculates the draught risk and the degree of turbulence in accordance with EN ISO 7730/ASHRAE 55.
For convenient measurements at varying heights, we recommend using our measuring tripod for comfort level measurement (please order separately). This makes it very easy to position turbulence probes in compliance with the standards.

Range of probes for cleanrooms and laboratories

The testo 440 air velocity & IAQ measuring instrument is also ideal for a wide variety of applications in cleanrooms and laboratories in conjunction with the following probes:
  • High-precision flow measurement in fume cupboards with the fume cupboard probe
  • Thanks to the low start-up speed of 0.1 m/s, the high-precision vane probe (Ø 100 mm) is ideal for laminar flow measurements in cleanrooms. It is available as a variant with Bluetooth or with fixed cable
  • To measure the humidity in cleanrooms, we recommend the high-precision humidity/temperature probe (0636 9771 or 0636 9772). With an accuracy of ±(0.6 %RH + 0.7% of m.v.) (0 to 90 %RH), it also meets the requirements for humidity measurements in this particularly sensitive area
  • Use the high-precision digital Pt100 temperature probes, for example, for high-precision comparative measurements in calibration laboratories, temperature measurements in chemical laboratories or in the cosmetics industry as well as for determining the temperature distribution in refrigerators and conditioning cabinets