Converting a continuous count of days into excel formatted dates.
1. Firstly, you need to know what date your numbers start from. In my example, 1 = 1st January 2008, and 1 day is equal to the number 1, so 2 = 2nd January 2008, 32 = 1st February 2008 and so on.
The numbers can start anyway: for example, Julian days start on 1st January 4713 BC; and Lilian days start on 15th October 1582 AD.
2. You also need to know that excel starts its dates on 1st January 1900,
so for excel 14th April 2023 = 45030
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3. This means you need to take your start date and subtract one from it, you need the day before the start date as this will be equal to zero.
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4. Change the number formatting in this cell to find out what number excel thinks this date is. In my case 31st December 2007 is equal to 39447
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5. Then take the number from Step 4 and add your numbers to it.
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6. Finally, use the keyboard shortcut Ctrl + 1 to open the Format Cells box and change the number format to the date format that you want.
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Final Result
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