How do I calculate the grand total in a matrix differently to the way the column is calculated

[AlixB]

I have a matrix where I have 2 calculated measure columns:

Available Hours = sum('Dates'[Hours])-(sum('Reliability Data'[Planned Outage])+sum('Reliability Data'[Unplanned Outage]))

and

Availability = IFERROR((sum('Dates'[Hours])-sum('Reliability Data'[Planned Outage])-sum('Reliability Data'[Unplanned Outage]))/(sum('Dates'[Hours])),1) 

They produce a percentage or value of total time available of the total time once time outages are removed.

so the way the grand totals are calculated is done in exactly the same way, however it is meaningless and needs to be an average of the columns vlaues.

How do I get the totals as an average rather than the same calculations as the rest of the column?

[Mohammad_Refaei]

Try this:

Availability =
VAR MyVar =
    IFERROR (
        (
            SUM ( 'Dates'[Hours] ) - SUM ( 'Reliability Data'[Planned Outage] )
                - SUM ( 'Reliability Data'[Unplanned Outage] )
        )
            / ( SUM ( 'Dates'[Hours] ) ),
        1
    )
RETURN
    IF (
        ISINSCOPE ( 'Reliability Data'[TAG] ),
        // [TAG] or any field you will use in your matrix
        MyVar,
        AVERAGEX ( 'Reliability Data', MyVar )
    )

[AlixB]

Unfortunately that returns the same results as I currently have in both the column and the total

[Mohammad_Refaei]

Then try this:

Availability =
VAR MyVar =
    IFERROR (
        (
            SUM ( 'Dates'[Hours] ) - SUM ( 'Reliability Data'[Planned Outage] )
                - SUM ( 'Reliability Data'[Unplanned Outage] )
        )
            / ( SUM ( 'Dates'[Hours] ) ),
        1
    )
RETURN
    IF (
        ISINSCOPE ( 'Reliability Data'[TAG] ),
        // [TAG] or any field you will use in your matrix
        MyVar,
        MyVar
            / COUNTROWS ( SUMMARIZE ( 'Reliability Data'[TAG], 'Reliability Data'[SYSTEM] ) )
    )