Difference between two datetime values in format dd:hh:mm:ss

Hi,

i think your problem is Milliseconds which are in your datetime.

You have to extract Text before delimiter in each column using . as delimiter

(and if you prefer in the same step change type text to type datetime)

 = Table.TransformColumns(#"Changed Type", {{"Column1", each Text.BeforeDelimiter(Text.From(_, "it-IT"), "."), type datetime}})

then you use your formula

and it will be all right

When you change finally the type you need to use Duration and not Datetime.

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p.s.: pay attention to the fact that you will not be able to use duration in your report (when you load your duration is converted to decimal). Refer to this in order to handle this problem

https://community.powerbi.com/t5/Desktop/Duration-format/m-p/447543