Extech 45158 Mini Thermo-Anemometer with Humidity


Extech 45158 Mini Thermo-Anemometer with Humidity The dual display indicates Air Velocity and Humidity, Dew Point, Ambient Temperature, or Temperature with wind-chill factor. 



  • Display air velocity and either Relative Humidity, Dew Point, Temperature or Windchill
  • Selectable averaging function of
  • 5, 10, or 13 second intervals
  • Fold up protective housing extends to 9" (229mm) for better reach, Tripod mount
  • Data Hold with Auto power off
  • Water resistant housing floats

Waterproof Mini Thermo-Anemometer + Humidity

Model 45158 packs a lot of capability into a pocket size meter that displays air velocity plus temperature or air velocity plus relative humidity on a large, dual display LCD.

Features & Functions Overview

Wind speed values are displayed in six different units (feet/minute, meters/second, kilometers/hour, miles/hour, knots, and Beaufort) with +3% accuracy. Averaging for 2, 5, or 10-second intervals can be selected. Besides air velocity, it also measures wind chill plus relative humidity, and dew point. Additional Functions: Other features include Data Hold to freeze the most recent display, and Auto Power Off to preserve battery life. The 5-1/4" meter folds into a water-resistant housing that is designed to float and when the cover is open. The meter extends to 9" for reaching into openings. You’ll want to carry it with you whether you are on the job as an HVAC or plant maintenance technician or involved in recreational sports.

Anemometers measure moving air with a rotary sensor that acts very much like a weathervane and can be likened to the blades of a fan. The vane freely rotates in response to airflow, and as the air moves through the vane the blades turn in proportion to the speed of the air.

Cubic Feet per Minute (CFM) or Cubic Meters per Minute (CMM) are units of measure for air volume measurements. This is a measurement of the quantity of moving air through an air duct, passageway, or enclosure. In order to determine this, the area of the duct must be measured. The area value (in ft2 or m2) is entered by the user, by pushbutton or keypad into the meter and an air velocity is determined.

Click here for product datasheet


MPH (Miles per hour)
Range 1.1 to 62.5 MPH
Resolution 0.2 MPH
Accuracy ± (3% + 0.4 mph)
km/hr (kilometers per hour)
Range 1.8 to 100.6 km/h
Resolution 0.7 km/h
Accuracy ± (3% + 1.4 km/hr)
Knots (nautical miles per hour)
Range 1.0 to 54.3 knots
Resolution 0.3 knots
Accuracy ± (3% + 0.6 knots)
m/sec (meters per second)
Range 0.50 to 28.00 m/s
Resolution 0.01 m/s
Accuracy ± (3% + 0.2 m/s)
ft/min (feet per minute)
Range 100 to 5500 ft/min
Resolution 20ft/min
Accuracy ± (3% + 40 ft/min)
Beaufort force
Range 1 to 17 BF
Resolution 1 BF
Accuracy ± 1
Range 0° to 122°F (-18° to 50°C)
Resolution 0.1°F/C
Accuracy ± 1.8°F (± 1°C)
Relative Humidity
Range 10 to 95%
Resolution 1%
Accuracy ± 5% RH
Dew Point
Range 32° to 122°F (0° to 50°C)
Resolution 0.1°:F/C
Accuracy ± 3.6°F (2°C)
General Specifications
Display Dual LCD with low battery and multifunction indicators
Sensors Sapphire bearing, non-corrosive vane for air velocity; Precision thermistor for temperature measurements
Average Mode Choice of 5 or 10 reading averaging (2 second factory default)
Max and Data Hold Displays Max recalls the highest reading; Data Hold freezes the display
Sample time 1 reading per second for air velocity and temperature (1 reading per 15 seconds for humidity with 2 second updates)
Water-resistant To 3’ (1m)
Operating conditions 5° to 122°F (-15° to 50°C) / < 80% RH
Power supply Lithium battery (CR-2032 or equivalent) / 400 hour battery life)
Dimensions / Weight Instrument 5.25 x 2.75 x 0.75” (133 x 70 x 19mm)
Vane 1” ( 24mm ) diameter / 3 oz. ( 95 g )


Product Images (click to enlarge)
  • Extech 45158 Mini Thermo-Anemometer with Humidity