Mqttv1 incoming value addition in item

[rossko57]

Then you should at least look at the docs (v2 docs have moved/archived)

Items

or you might see how others do it

[SOLVED] Rule to apply an offset to get an accurate temp reading

Use a profile: See: Number:Temperature Lounge_Hue_Temp "Temperature [%.1f °C]" <temperature> { channel="hue:0302:00178829a0c5:43:temperature" [profile="offset", offset="10"] } No rules and proxy item needed!!