HT607 Temperature Humidity Meter High Precision Digital Hygrometer with Ambient, Relative Humidity, Dew Point, Wet Bulb Thermometer, Min/Max Hold, LCD Backlight with Cover Protector

It’s largely a matter of faith as to whether any hygrometer is giving accurate readings. There are ways of calibrating them, but these aren’t all that reliable for a variety of reasons, like the fact that calibrating at one humidity level doesn’t guarantee accuracy at other humidity levels. That’s due to the fact that errors are nonlinear (not always off by a constant amount). Errors can be small (or even zero) over some portion of the range and large at others. Most home calibration methods, like the salt method, calibrate at the high extreme of the range, when our concern may be for accuracy elsewhere in the range.That issue is a tough one to get around, but digital sensors seem to have gotten better. In any case, taking any value of relative humidity as the gospel truth is a questionable proposition.What I look for is patterns of change in displayed RH as the environment changes and, to some degree, concurrence among multiple indicators. That’s where this unit seems to excel. It gives me a reading that tracks (notice I didn’t say “agrees”) with other devices I have and with changes in the environment, such as running the heat like crazy and/or running a humidifier. Also, repeat measurements are reasonably stable under unchanging conditions. So, the readings are reliable (notice I didn’t say “accurate”).The various bits of information the unit provides are convenient. For example, the dew point is sometimes more informative than the RH. This unit displays that.To sum up, even though I have no certainty that the readings this hygrometer gives me are precisely accurate RH values, I think it does about as well as you can expect in a consumer-grade product. It’s consistent, easy to use, easy to read, compact, and affordable. If you need more than that, then you probably should be looking at laboratory equipment rather than something like this hygrometer. I like it and recommend it for most uses outside of a laboratory. It might even be fine in a lab but I’d need further validation tests to know that. In the real world, at affordable prices, in a convenient form factor, I think this is pretty much as good as it gets. [...]