ExtechDigit Thermometer

The Extech 445715 Digital Thermometer is a solid purchase if you need accuracy. I use it for everything from cooking to checking room temperatures, and it’s always spot-on. The display is clear, and the device itself feels well-made and durable. It’s quick to respond, and the easy-to-use buttons make it simple to operate. If you need a reliable thermometer, this one’s definitely worth it!

Works great in my music studio. Guitars require between 40-60% humidity. This is perfect measuring device for me.

Works as stated and numbers are a nice size.

I just installed a whole house dehumidification system in my home and needed 2 hygrometers for the main floor and the basement. I wanted to buy an accurate unit with a large print digital display. Thus far, the temperature tracks right on target with my expensive furnace thermostat. I have nothing to check the accuracy of the humidity readings, but assuming they are fairly accurate, I was able to adjust my Aprilaire humidity setting to keep the humidity levels at ~ 50% in both locations. The unit has a fold up stand on the back of it so I did not choose to wall mount them. I placed one of them on a book case shelf in my great room and one on my office desk in the basement. I also like the mount of the sensor on the outside of the unit which produces a more accurate humidity reading. I have used the Extech units for 1 month, but I am extremely satisfied with their performance to-date. They are more expensive than many others, but always believe that most of the time you get what you pay for by spending a little more money. In this case, I am protecting my entire home against humidity damage and was willing to pay more for a quality product. As usual, Amazon's pricing was better than the competition for this product. I can't testify that there wasn't a better price out there, but the price was good and Amazon's excellent shipping policy for Prime customers made the decision easy.

After my (very unofficial) home testing of this unit, I find it acceptable for the typical home use. Other posters here have done much more exhausting analysisTemp readings are right on, and the unit is very responsive. RH (relative humidity) readings are close enough to satisfy my needs.Not a bad unit, but not a true scientifically accurate tool to be sure. I can only offer 4 stars because I believe that the claims for this unit are a bit rosy.Decent buy though. Get one.CARPE DIEM

Have had my Extech 445815 for 15 years. Temperature was accurate. RH was OK and sensitive. This winter my Extech RH readings were way off, so I decided to calibrate RH. As an engineer, I am familiar with using saturated salt solutions to calibrate instruments.Unfortunately, as others have discovered and commented on, and despite Extech's claims to the contrary, the RH adjustment did nothing. My own pure sodium chloride saturated salt test gave a meter reading of 59% RH at 70 degrees F - way off. I turned the humidity adjustment screw. No change in RH reading. The screw just turned and clicked every so often. No difference which way turned.Extech sells a very expensive humidity calibration kit, but if you cannot actually adjust the calibration then that kit is not worth the price. It will only tell you if your meter is close or completely off. Despite Extech's claims otherwise, you can do your own testing easily and cheaply as there are well researched and standardized test values available for using different saturated salts with RH values at various ambient temperatures.My conclusions: I enjoyed having this meter for many years. Loved having Dew Point as that is much more valuable than RH. Was looking forward to more years with a calibration. However, RH calibration screw just turns and does nothing.I will not buy an Extech replacement. I don't know, but perhaps their NIST certified models have RH calibration potentiometers that work. Extech's written product statement about ability to adjust the 445815 RH calibration is clearly wrong. Three stars as I did get years of use, but expensive for just a temperature-relative humidity meter.

I bought this to more accurately measure humidity levels inside the house. The manufacturer rates the humidity accuracy at +/- 4%. Most products at this price point or less don't specify the accuracy at all for humidity. The external sensor is extremely sensitive to humidity changes. I have not verified the accuracy of the readings as of yet but may do so in the future. Also, there is a calibration adjustment on the back so you can dial it in if need be, but I believe they are tuned at the factory so its really not necessary. The min max feature is nice to get a snap shot of how much temperature and humidity varies overnight or a longer period of time. This is probably one of the best I've seen at this price point.