How accurte are the DHT11 Sensors?

Hi guys,

I have a couple digital humidity meters around the house. They all measure RH within 5%.

A DHT11 measures 20% less than these. So if the digital RH meters are displaying 66% the DHT is measuring around 45%.

One thing I find awkward is that on the DHT11 the dew point is calculated just above 0C. My windows have condensation on areas at which the temperature is below 4.5C, so for a start the dew point of 0C is wrong.

Any ideas what could be causing this? I have two sensors, so that rules out a faulty one.

There is an old thread where people reported this issue, but apparently no solution found?

Thanks

If you DHT11 is 20% less, then you have a good DHT11. My DHT11 are a lot worse than that. The DHT22 is barely better. I think it has to do with the sensor itself, I read it is sensitive for certain chemicals that are used in packaging plastics.
Use a capacitive humidity sensor, or search at Adafruit.com for a better sensor.