Sumarize per Month sliced downtime

This one was a bit crazy, so try to stick with me...  ** Make sure all Date / Time columns are formatted as such! **

First, I needed to create a boarder table I called 'Months'.  Since we are looking at Minutes instead of days, I had to take this down to the Time level where every month starts at 00:00:00 and every month ends at 23:59:59.  You can do this easily in excel or by hand (it won't take that long.)

Here is your data:

I needed a good way to apply If / Then logic to each of your  dates to see how they merge into the different months.  I did this by creating a new Custom Table (not in Query Editor) under the Modeling Tab of Power BI.  This CrossJoin command will mesh the two tables together for every row.

Now I can start throwing math against the problem.. here are my 4 custom columns to account for periods starting during a month, a full month, or periods ending during a month.  Then a Total for easy visuals:

PartialMonthStart = IF('Table'[StartMonth] <= 'Table'[Start] && 'Table'[EndMonth] >= 'Table'[Start],DATEDIFF('Table'[Start],'Table'[EndMonth],MINUTE) + 1 )

FullMonth = IF('Table'[StartMonth] >= 'Table'[Start] && 'Table'[EndMonth] <= 'Table'[End],DATEDIFF('Table'[StartMonth],'Table'[EndMonth],MINUTE) + 1)

PartialMonthEnd = IF('Table'[StartMonth] <= 'Table'[End] && 'Table'[EndMonth] >= 'Table'[End],DATEDIFF('Table'[StartMonth],'Table'[End],MINUTE) + 1 )

*** The +1 at the end is VERY important, b/c eadh day ends at 23:59:59, I have to manaully add in the missing full minute. ***

TotalMinutesDown = 'Table'[PartialMonthStart] + 'Table'[FullMonth] + 'Table'[PartialMonthEnd]

Now that you have mutple lines per Month, you can easily create a Visual SUM'ing the Total Minutes column.  See below where I have the raw data (with a calculated Durration Minutes, and then my chart with a matching SUM when looking at the values by month.

Thank You,

FOrrest