If you've ever had to figure out which of the year's 365 days a particular date falls on, or how many days remain in the year, you've probably found that Excel lacks functions to perform the calculation. But you can create formulas to do the job. The formula below returns the day of the year for a date in cell A1:

Excel automatically formats the cell as a date, so change the number format to another option (like General).

To calculate the number of days remaining in the year (assuming that the date is in cell A1), use the following formula: