The calibration helper corrects a sensor that reads off. A temperature sensor that is always a degree too high, a humidity sensor a few percent too low, or a power plug that measures 10% too much: the helper gives you a new sensor with the corrected value.
How it works¶
The helper takes the value of the source sensor, multiplies it by the factor, and adds the offset:
corrected = value × factor + offsetMost of the time, an offset is all you need. A sensor showing 21.3 °C while it is really 19.8 °C gets an offset of -1.5, and leaves the factor at 1. The factor is for sensors that are off by a percentage instead: a plug showing 110 W while it really uses 100 W gets a factor of 100 ÷ 110, so 0.909. Divide what it really is by what the sensor shows.
The new sensor takes the unit, device class and state class of the source. Graphs and long-term statistics work the same as for the source.
When the source is unavailable, unknown, or not a number, the calibrated sensor is unavailable. It does not make up a number.
The new sensor is added to the same device as the source.
The offset is in the unit the source reports in. If you change the unit of the source later on, like from °C to °F, change the offset too.
Creating a calibration helper¶
Add one directly to your own instance by selecting the My Home Assistant button below:
Or add one manually, using the following steps:
From the Home Assistant sidebar, select Settings and next select Devices & Services.
Select the Helpers tab.
On the helpers page, in the bottom right corner, select the + Create helper button.
From the list of helpers, select Calibration 👻.
Provide a name, and select the sensor to correct in the Source entity field.
Fill in the Offset, and if needed the Factor.
Select Submit. Done! 🎉
Want to see only the corrected sensor? Hide the source sensor in its entity settings.