Site Information

 Loading... Please wait...
You are using an outdated browser. Please upgrade your browser at to improve your experience.
Product Info

Extech RH390 Precision Psychrometer

EXT079 |

| Click Here to Learn How to Use This Desk Builder

Selected But Not Shown

      The Extech Precision Psychrometer RH390 has a high 2% RH accuracy, a fast response time, less than 30 seconds, and a dual backlit display.

      The RH390 can simultaneously display humidity and temperature, humidity and dew point, or humidity and wet bulb measurements.


      • Offers a dual backlit display
      • Made with a slim design complete with rubberized sides for better grip and for one hand use
      • Includes Data Hold and Min/Max functions
      • Auto-powers off with disable feature
      • Alerts user with low battery indicator
      • Has a simultaneous display of humidity/temperature, humidity/dew point or humidity/wet bulb


      Humidity 0 to 100%RH
      Internal Temperature -4 to 199°F (-20 to 100°C)
      Basic Accuracy ±2%RH, ±1.8°F/1°C
      Max Resolution 0.1%RH, 0.1°F/°C
      Dewpoint -22 to 199°F (-30 to 100°C)
      Wet Bulb 32 to 176 °F (0 to 80°C)
      Dimensions 7.8" H x 1.7" W x 1.3" D
      Weight 7 oz (200g)

      NIST Calibration

      The Extech RH390 Precision Psychrometer is available with standard factory calibration or with NIST Calibration Certification (adds 5 days to product lead time). NIST certification offers a traceable certificate that satisfies ISO & other regulatory requirements for product accuracy traceability to nationally recognized reference standards.

      Product Reviews

      Write Review

      1. Excelent Product 5 Star Review

        Posted by on Jun 1st 2010

        Precision and good product

      2. Excelent Product 5 Star Review

        Posted by on May 28th 2010

        Excelent Product, Price/Value, as its named Precision

      Warranty Information

      Please see our warranty page for more information regarding the warranty on this item.

      Return Information

      • Return windows close 30 days after you receive your item.
      • You are responsible for obtaining a Return Merchandise Authorization, the cost of shipping, and potential restocking fees, if the item has been opened.
      • To start a return, or to view the full returns policy, click here.
      Your Cost $199.99 List Price:
      Ships Free (US48)
      Ships the next business day

      Click the button below to add the Extech RH390 Precision Psychrometer to your wish list.

      Please Note: Adding items to your wishlist will not save your custom configuration. If you would like to save your current configuation, you can email it to yourself, or copy the link below.

      Are you sure you're finished customizing this product?

      No, Continue Building
      Yes, Add To Cart Now

      Bulk Deals

      In many cases, we can offer bulk quantity discounts for purchases or smaller orders made over an extended period of time. Bulk deals are based on anticipated volume and the products you've selected. We can also provide you with brochures and swatches to assist in your purchasing decisions.

      If you would like to request a quote, we can be reached via phone (800-531-3746), email (, or live chat from 8am - 7pm Monday - Friday and from 10am - 6pm Saturday.

      Swatch Request Form

      Thank You!

      Please allow 1-3 weeks for delivery.

      Please Select Swatches