AirGradient Forum

Open Air Outdoor Air Quality Monitor - Humidity readings are off

#1

Hi,

I’ve place three different monitors in the same room to compare the measures:

  • an airgradient outdoor DIY monitor
  • an airgradient indoor DIY Pro monitor
  • and an amazon monitor

All monitors measures are close except for the relative humidity returned by the outdoor monitor. It’s off by about 25% compared to what the other two return.

Is there some kind of calibration that I can do ?

Thanks,

JP.

Edit: wording

#2

The raw humidity readings from the plantower PMS5003T are off by around 20-25%.

You can use the following correction formula:

Humidity Compendated = 1.3921 * Humidity from sensor - 1.0245
Example: 57.44 = 1.3921 * 42 - 1.0245

1 Like
Outdoor Temperature and humidity reading correction
#3

I’ve just applied these factors to my Open Air device and the resulting humidity readings appear to be correct, so thanks for that!

I wonder why the factors in this post are different from the ones in the blog post on the same topic?

#4

The correction formulas are based on different data sets with different ranges of humidity. We are still collecting data and will come up with improved algorithms over time.