Date Difference Calculator
Find the number of days, weeks and months between two dates.
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Pick a start date and an end date and this calculator returns the number of days between them, along with the same span in weeks, approximate months and approximate years. It is useful for notice periods, loan and FD tenures, visa stays, project timelines and checking how old an unpaid invoice is.
How the day count works
The tool counts the number of midnights between the two dates, which means the start date is included and the end date is not. From 1 January to 31 January gives 30 days, not 31. That is the convention for durations such as hotel nights or "days since", but for leave applications or event days where both the first and last day count, add 1 to the result.
A few more details:
- The order does not matter. If the end date is earlier than the start date, you still get a positive number of days.
- Leap years are handled automatically: 1 February to 1 March 2024 returns 29 days.
- Only dates are compared, not times, so time zones and daylight saving do not affect the answer.
Where the weeks, months and years come from
| Line | Formula | Rounded to |
|---|---|---|
| Weeks | days ÷ 7 | 1 decimal |
| Months (approx) | days ÷ 30.44 | 1 decimal |
| Years (approx) | days ÷ 365.25 | 2 decimals |
30.44 is the average length of a month over the 400-year Gregorian cycle (365.2425 ÷ 12), and 365.25 averages in one leap day every four years. Because real months run from 28 to 31 days, these lines are approximations. If you need an exact "2 years, 5 months and 11 days" style breakdown, the age calculator counts calendar months properly.
Worked example: Independence Day to Republic Day
Start date 15 August 1947, end date 26 January 1950, the day India's Constitution came into force:
- Difference: 895 days
- Weeks: 895 ÷ 7 = 127.9
- Months: 895 ÷ 30.44 = 29.4
- Years: 895 ÷ 365.25 = 2.45
A second check shows the end-date rule clearly. The Indian financial year 1 April 2026 to 31 March 2027 returns 364 days; counting both ends makes it the full 365.
Common uses and mistakes
- Notice period or deadline: if you know the start and the length (say 90 days) and need the end date, the add or subtract days tool is the right one.
- Working days: this count includes weekends and holidays. For office days only, use the business days calculator.
- Visa and stay limits: immigration rules often count both the arrival and departure day, so add 1 before comparing with the permitted number of days.
- Month-based contracts: a rent agreement "for 11 months" follows calendar months, so do not rely on the approximate month figure to find its end date.
- Years of service: the approximate years figure can round the wrong way near a boundary, so take the exact years and months from the age calculator before entering them in the Gratuity Calculator.