Opportunity stage duration

nanma94 try measure below and here is the result.

Days between Stages = 
VAR __oppyId = SELECTEDVALUE ( Oppy[OpportunityId] )
VAR __Stage = MAX ( 'Oppy Detail'[Stage #] )
VAR __StageDate = MAX ( 'Oppy Detail'[CreatedDate] )
VAR __prevStage = MAX ( __Stage - 1, 1 )
VAR __prevStageDate = 
CALCULATE ( 
    MAX ( 'Oppy Detail'[CreatedDate] ),
    ALL ( 'Oppy Detail' ), 
    Oppy[OpportunityId] = __OppyId, 
    'Oppy Detail'[Stage #] = __prevStage 
)
RETURN DATEDIFF( __prevStageDate, __StageDate, DAY )

Would appreciate Kudos 🙂 if my solution helped.