how do I sum depending on the background color of cells in Excel?

[Erik MITON]

I would like to summarize numbers depending on the color i set in the
conditional formatting -

meaning sum all REd cells, sum all Green Cell, ....etc

 

[Pete_UK]

If you are using conditional formatting to set those colours then you
can apply the same condition within a formula to add them up - a
simple SUMIF, or SUMPRODUCT formula, depending on the complexity of
the condition. Perhaps if you can give us the conditions that you are
using ... ?

Pete