[HELP] Text item with result of calculation

Hi,

I would like to have a sitemap item that shows the money I pay per hour. The source information is taken from a Zwave Fibaro wall plug which gives me information about power (watts, Kwh).
So I would like to make a simple math calculation and make it appear in my sitemap…

How could I do it? with transforms? with rules?..

Thank you in advance

Rules.

Create a Rule that triggers when the wall plug Item is updated. Perform your calculation and postUpdate the result to another Item. Put this other Item on your sitemap as a Text element.

Thank you very much,

I’ll try it out