There are a couple of solutions here: https://community.safe.com/s/question/0D54Q000080hNiUSAU/converting-floating-point-date-based-on-1900-date-system

This one had me stumped for a while, as my results kept being one day off. But it turns out all Excel versions have a deliberate bug: 1900 is considered to be a leap year(!). Apparently this was done for better compatibility with the once famous Lotus 1-2-3.

Of course all Excel functions niftily work around this real Year 1900 Bug! For more information see here.

Also bear in mind that 1-1-1900 is day 1 (not 0).

Please note: This solution gives a wrong date for all 59 days in januari and februari 1900. I hope this is not a problem ;-)

HI all, thanks for the feed back, I was able to get it solved using a combination of both of your response.