testo 400 - Universal Air Flow and IAQ Instrument

Order-Nr.  0560 0400

  • A measuring instrument for all climate-related parameters

  • Smart, intuitive measurement programs including HVAC grid measurement as per EN ISO 12599 and ASHRAE 111, PMV/PPD and turbulence as per EN ISO 7730 and ASHRAE 55

  • High-precision, location-independent and integrated differential pressure sensor

  • Extendible with a wide range of probes

  • Analytical software for creating professional reports and measurement data management

  • Digital probes eliminate any additional measurement uncertainty of the measuring instrument

The testo 400 is the universal measuring instrument for all TAB / Commissioning and IAQ professionals. Measure, analyze and document Air flow, air pressure,  IAQ and comfort level parameters using just one instrument – simply, conveniently and in compliance with the standards. High-quality measuring technology, intuitive measurement assistants, versatile documentation options and a comprehensive selection of air flow, comfort and IAQ probes make the testo 400 the perfect partner for your day-to-day work.


A measuring instrument for all climate-related parameters


Product Description

As an expert in the field of air conditioning and ventilation, you will find the testo 400 universal Air flow and IAQ measuring instrument ideal. The measuring instrument with a built-in measurement assistant provides optimum support for carrying out air flow and comfort level measurements in accordance with the standards like NEBB and ASHRAE, as well as for Testing,  Adjusting & Balancing (TAB) air conditioning and ventilation systems.

testo 400 universal Air Flow and IAQ instrument – features:

Impressive IAQ measurement technology
  • High-precision, location-independent and integrated differential pressure sensor meeting the NEBB Instrument requirements for Air pressure
  • Integrated absolute pressure sensor
  • Measures all IAQ-related parameters: Flow, temperature, humidity, pressure, illuminance, radiant heat, turbulence, CO2 and CO
  • Numerous connection options for probes: 2 x cable probes (TUC), 4 x Bluetooth® probes, 2 x type K thermocouple probes
  • Compatible with a wide range of available Bluetooth® and cable probes – so you’ll be equipped for any measuring task
  • For high-precision measurements and less downtime: Adjustment function at up to six measuring points for zero-error display, probe heads can be replaced without restarting the IAQ measuring instrument, high-quality probes with an intelligent calibration concept (probe calibration independent of the measuring instrument)
  • Long-term monitoring of the indoor air quality: Order the IAQ data logger for carrying out long-term measurements with the testo 400 IAQ measuring instrument. While the stand-alone data logger is carrying out the IAQ measurement, you can use the IAQ measuring instrument for measurements elsewhere
Smart, intuitive, practical: Measurement programs, measurement data management and operation
  • For error-free measurements in accordance with the standards: Smart, intuitive measurement menus and evaluation of readings according to the traffic light principle provide optimum support for your measuring task. Use the measurement programs for standard-compliant measurements: HVAC volume flow grid measurement as per ASHRAE 111, PMV/PPD as per ASHRAE 55, draft and turbulence as per ASHRAE 55
  • Complete the measurement and full documentation including photos, comments and your own logo on site at the customer’s premises, and send by e-mail (via WiFi)
  • Customer and measuring point management is carried out in the measuring instrument itself – for efficient work on site
  • Smart-touch display for intuitive operation of the IAQ measuring instrument
  • testo DataControl PC software for further analysis, archiving and documentation of measurement data on your computer
  • Built-in WiFi and Bluetooth® interfaces: Send measurement reports directly on site or print them out with a suitable printer

Delivery Scope

  • testo 400 universal instrument (0560 0400)
  • Transport case for air flow measurement (0516 1400)
  • Power supply with USB cable (0554 1106)
  • testo DataControl software
  • Calibration protocol

Technical Data

Temperature - NTC

Measuring range

-40.0° to 302.0 °F / -40 to +150 °C


±0.4 °F ±1 Digit (-13° to 166.8 °F) / ±0.2 °C ±1 Digit (-25 to +74.9 °C)

±0.7 °F ±1 Digit (-40° to -13.2 °F) / ±0.4 °C ±1 Digit (-40 to -25.1 °C)

±0.7 °F ±1 Digit (75° to 211.8 °F) / ±0.4 °C ±1 Digit (+75 to +99.9 °C)

±0.5 % of mv ±1 Digit (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 + 0.1 % of mv) ±1 Digit / ±(0.3 °C + 0.1 % of mv) ±1 Digit


0.1 °F / 0.1 °C

Differential pressure (internal sensor) - Piezoresistive

Measuring range

0 to +80 InH₂O / 0 to +200 hPa


±(0.0 InH₂O + 1 % of mv) ±1 Digit (0 to 25 InH₂O) / ±(0.3 Pa + 1 % of mv) ±1 Digit (0 to 25 hPa)

±(0.0 InH₂O + 1.5 % of mv) ±1 Digit (10.000 to 80 InH₂O) / ±(0.1 hPa + 1.5 % of mv) ±1 Digit (25.001 to 200 hPa)


0.000 InH₂O / 0.001 hPa

Absolute Pressure (internal sensor and external probe)

Measuring range

280 to 440 InH₂O / 700 to 1100 hPa


±1 InH₂O / ±3 hPa


0.1 InH₂O / 0.1 hPa

General technical data


17.99 oz. (instrument) / 510 g (instrument)


8.3 x 3.7 x 1.5 in. ((LxWxH)) / 210 x 95 x 39 mm ((LxWxH))

Operating temperature

23.0° to 113.0 °F / -5 to +45 °C



Protection class


Connectable probes

4 x digital Bluetooth® probe or testo Smart Probe; 2 x digital probe with fixed cable or temperature probe NTC with fixed cable (via Testo Universal Connector - TUC); 2 x temperature probe TC type K with fixed cable

Product colour


Camera image size

Main camera: 8.0 MP; Front camera: 5.0 MP

Battery life

approx. 10 hrs continuous operation

Display type

5.0" touch display, HD 1280*720 pixels, IPS (160 k)

Power supply

Rechargeable li-ion battery (5550 mAh)


Bluetooth®; USB; WLAN


2 GB; 1,000,000 measuring values

Storage temperature

-4.0° to 140.0 °F / -20 to +60 °C

*TUC connection (Testo Universal Connector): For the connection of fixed cable digital probes and NTC probes.


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
$ 3,699.00
excl. tax





Transport case for air flow measurements

Order Number: 0516 1400

$ 249.00
excl. tax
$ 425.00
excl. tax
USB mains unit, including cable

Order Number: 0554 1106

$ 577.00
excl. tax


Air flow and IAQ measurements in the field of air conditioning and ventilation

  • Air flow measurements: Flow measurements in ducts, at outlets and on filters as per ASHRAE 111
  • High-precision, location-independent and built-in differential pressure sensor, smart and intuitive measurement programs for IAQ measurements in accordance with the standards, creation of documentation on site, e-mailing of reports, versatile combination options with IAQ probes
  • Measurements in laboratories and cleanrooms: Flow measurements in fume cupboards, differential pressure measurements and laminar flow measurements in cleanrooms, humidity measurements in cleanrooms
  • Comfort level measurements: Measurement of indoor air quality or turbulence as per ASHRAE 55, NET measurement as per DIN 33403, PMV/PPD as per ASHRAE 55