Updated June 17, 2026
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To find the number of days between two dates, convert both to a day count from a fixed reference point and subtract. In a spreadsheet, subtracting one date cell from another gives the answer directly, no formula required.
The manual method
For dates within the same year, count the days left in the start month, add the full months between, and add the days in the final month. For anything longer, a calculator or spreadsheet is the right tool, because you also have to account for months with 28, 29, 30, or 31 days.
In Excel or Google Sheets
With two date cells (e.g. A1 and B1), the formula is simply =B1-A1. Format the result cell as a number, not a date, and it returns the exact number of days. You can also use =DAYS(B1,A1) for clarity.
Days between dates in months
To convert days to complete months, use =DATEDIF(A1,B1,"M") in Excel. This returns full calendar months, not an approximation. For a partial count including remaining days: =DATEDIF(A1,B1,"MD") gives days left over after whole months.
Why do people need a days calculator?
Common uses: days until an event, contract deadline verification, figuring out how long ago something happened, and interest calculations on daily-rate loans. Also, arguing about how many days until a birthday. (People are competitive about this.) The Date Calculator handles all these cases and shows the result in days, weeks, and months. See also how to calculate age for a related use case.
Leap year considerations
A leap year adds February 29, occurring roughly every four years. If your date span crosses one or more leap year Februaries, the count is one day higher per leap year than a simple 365-per-year estimate. This matters most for spans of several years.
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