Rounding in template has wrong number of decimals

Configuration
1

Hi,
i have the following template sensor:

  feinstaub_luftdruck_hpa:
    value_template: '{{ states("sensor.feinstaub_luftdruck") | float / 100 | round(2) }}'
    friendly_name: "Luftdruck"
    unit_of_measurement: "hPa"

As you can see, i’d like to round the result of the division with 100 to a value of two decimals. However, i seem to be unable to do this. Currently, the value of this template sensor is: 1007.0975999999999 while the raw value of the sensor input for the template is 100709.76. I do not understand where the suffix of 9 comes from. It looks like a rounding error. Sometimes the value is displayed correctly, but with four decimals, and not with two decimals, like desired. Where is my error?

2

The way you wrote it, the rounding is applying just to 100, not the entire equation before it. So you have to use parentheses:

'{{ (states("sensor.feinstaub_luftdruck") | float / 100) | round(2) }}'

I’ve gotten bitten by this myself.

4 Likes
3

OK, thanks. I’ve got it now :slight_smile:

4

Thanks for posting that, was having the same issue.