Solution without extra columns?

Hi IAM ,

We assum data looks like this:

create a measure to calculate the average days.

Measure =
VAR _s1 = "creation"
VAR _s2 = "planned"
VAR _s3 = "actual"
VAR _s1_s2 =
    VALUE (
        CALCULATE (
            MAX ( 'Table'[start date] ),
            FILTER ( ALLSELECTED ( 'Table'[status] ), [status] = _s2 )
        )
            - CALCULATE (
                MAX ( 'Table'[start date] ),
                FILTER ( ALLSELECTED ( 'Table'[status] ), [status] = _s1 )
            )
    )
VAR _s2_s3 =
    VALUE (
        CALCULATE (
            MAX ( 'Table'[start date] ),
            FILTER ( ALLSELECTED ( 'Table'[status] ), [status] = _s3 )
        )
            - CALCULATE (
                MAX ( 'Table'[start date] ),
                FILTER ( ALLSELECTED ( 'Table'[status] ), [status] = _s2 )
            )
    )
RETURN
    DIVIDE ( _s1_s2 + _s2_s3, 2 )

Pbix file in the end and hope this  helpful.

Best Regards

Community Support Team _ chenwu zhu

If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.