How to calculate Excel Timestamp as number


Excel stores date values as a number which allows you to perform calculations on dates. The Excel Timestamp is a variation on the Epoch timestamp where instead of calculating the days between 01/01/1970, Excel timestamp counts the number of days between date and 01/01/1900. The Excel timestmap is composed of 2 parts. Left of the decimal is the number of days between the date and 01/01/1900. Right of the decimal represents the time in seconds.

 Timestamp: 10/24/2017 14:31:08.860
 Excel Timestamp: 43032.6049636574

Days since 01/01/1900 = 10/24/2017-01/01/1900 + 1 = 43032
 Time in seconds 14:31:08.860 = [(14*60*60)+(31*60)+08.860]/86400=0.6049636574
 Excel Timestamp: Add the 2 numbers together = 43032.6049636574