Discussion about Units of Measurement

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(Vincent Regaud) #1

Hi Everyone,

I, for one, am really excited about the Units of Measurement feature.
There are a number of units already available in the code:

I have already added the pressure unit “bar” to the UoM

My question to you all is:

What units would you like to see added to the list?


(Harry) #2



(Vincent Regaud) #3

Thanks @hr3, Harry,
I have added bars in a pull request already, but what units would you find useful?

(Vincent Regaud) #4

Really, no one want to add units to the system?

Flow rates? Fuel Efficiency? pH?

(Rossko57) #5

Humidity? Not sure if that has a UoM technically, as it’s usually expressed as a percentage.
Checked, and yes there are ‘absolute’ humidty units. Conversion to RH% not possible without further information (temp).

Rotational speed? e.g. rpm. I have no use-case for that!

(Vincent Regaud) #6

You are correct technically but that’s already in the units


Number:Dimensionless Humidity "Humidity [%d %]"

(Marco Salinardi) #7

What about RAIN mm/hr?
And I’m using a custom absolut humidity in g/m³ that can be even espressed in g/kg (g of water on kg of air)

(Vincent Regaud) #8

And as the other thread you would like two more units of power VA and VAR, correct?
ApparentPower VA
ReactivePower VAR


(Vincent Regaud) #9

That would be a Speed quantity, Thanks

That would be a new Type of Density with the base unit as SI kg/m³

That would be a Dimensionless unit part per thousand (I plan to add this)

(Marco Salinardi) #10

yes and what about the speed Mbit/s or MByte/s?

(Vincent Regaud) #11

New unit type DataRate what should the base unit be? bit/s or byte/s

(Marco Salinardi) #12

Here they say the standard is B/s. b/s is only used when buying broadband from providers.
Must be kept in mind that the conversion between b/s to B/s is 8/1 and MB/s to B/s is 1024/1

(Vincent Regaud) #13

It’s the week-end.
Has anyone requests for units to be added to the Units of Measurements
I am thinking of our friends from the USA.

US gallons?


(Stephen) #14

Have a look at the Datapoint types in KNX’s Engineering Tool Software. That will give you a pretty comprehensive list of building control related units of measurement.

This list is a bit old but is a starting point!

(Rossko57) #15

Perhaps Nautical miles (distance), Knots (speed). Someone must have OpenHAB on a boat …

(Tommy Smith) #16

I need:
litre / second (l/s)
cubic meter / hour (m3/hour)

(Markus) #17

What about µS/cm?

The electric conductivity e.g. also for soil fertility measurement as is the case with the Miflora sensor.