=IF(B1="",TODAY(),B1)-A1
Format as number, not as date (which Excel will do automatically)

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Kind regards,

Niek Otten

"JulesM" wrote in message
...
I need an excel formula to calculated the number of days between 'Start
Date'
and 'End Date'. IF the 'End Date' is null I want to use todays date.

Please Help