Enter two dates to calculate the exact number of days, weeks, months, years, and total hours between them. Optionally include the end day in the calculation.
How to use this calculator
Select the start date using the date picker.
Select the end date using the date picker.
Choose whether to include the end date in the total count.
Read your total days, calendar breakdown (years, months, days), weeks, and hours.
Formula & method
Exact Calendar Difference Method
Total Days = (End Date − Start Date) in ms ÷ (1000×60×60×24) + [1 if inclusive]
Years, months, and days are computed by stepping through month lengths and leap years exactly.
Example
2026-01-01 to 2026-12-31 = 364 days (11 months, 30 days) or 365 days if inclusive.
Key insights
Calendar months vary from 28 to 31 days, so month counts depend on the specific months crossed.
Leap years add a 29th day to February, which is automatically accounted for in total day counts.
Including the end date counts both boundary days (e.g. Monday to Tuesday becomes 2 days instead of 1 day).
Business day calculations typically exclude weekends and public holidays, which can reduce total day counts by ~28%.
How to interpret your result
Total Days vs. Calendar Breakdown
Total days counts exact 24-hour periods, while calendar breakdown expresses the span in years, months, and remaining days.
Inclusive vs. Exclusive Dates
Standard date subtraction excludes the end day (Jan 1 to Jan 2 = 1 day). Inclusive counting adds 1 day (Jan 1 to Jan 2 = 2 days).
Frequently asked questions
How are leap years handled in date calculations?
Every February 29th that falls between the start and end dates is included in the total day count automatically.
Should I include the end date?
Exclude the end date for duration spans (e.g. hotel stays). Include the end date for event periods or inclusive day counting.
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