Date Difference Calculator
Exact time between two dates: total days, weeks, weekdays, and a calendar-accurate years, months and days breakdown.
What the date difference calculator does
The date difference calculator counts the time between two calendar dates. Pick a start date and an end date and press Calculate. The tool reports the exact number of days, the same span as weeks and days, the number of weekdays (Monday to Friday), and a calendar-accurate breakdown into years, months and days. A checkbox lets you include the end date when both endpoints should count.
How the result is worked out
All dates are handled in UTC so that daylight-saving changes cannot shift the count. The day total is the number of midnights between the two dates; leap days are included automatically. The years-months-days breakdown steps through the calendar: it counts whole years from the start date, then whole months, then the remaining days using the actual length of the month before the end date. From 31 January to 1 March is therefore reported as 1 month and 1 day in a common year (and 1 month and 1 day in a leap year, because February simply has one more day inside the month). Weekdays are counted by walking through the span and skipping Saturdays and Sundays; public holidays are not excluded.
The age calculator applies the same calendar logic to a birth date, and the date to date calculator adds or subtracts a period from a date.
Worked examples
| Start | End | Days | Breakdown | Weekdays |
|---|---|---|---|---|
| 1 January 2025 | 1 January 2026 | 365 | 1 year | 261 |
| 1 January 2024 | 1 January 2025 | 366 (leap year) | 1 year | 262 |
| 15 March 2025 | 4 July 2025 | 111 | 3 months, 19 days | 80 |
| 10 June 2020 | 10 June 2026 | 2,191 | 6 years | 1,565 |
Inclusive or exclusive counting
By default the calculator counts the nights between the dates, not the days touched. From Monday to Friday of the same week the answer is 4, which is the usual convention for hotel stays, loan interest and elapsed time. If your situation counts both endpoints, such as the number of calendar days a notice is displayed or the length of a rental in days, tick “Include the end date” and the result becomes 5.
Where the day count is used
- Project planning. Days remaining until a deadline, or the length of a phase between milestones.
- Finance. Interest on many loans and deposits accrues daily; the day count feeds directly into a simple-interest calculation.
- Legal and administrative deadlines. Notice periods, visa validity and warranty windows are usually expressed in days.
- Health and fitness. Days since a treatment started, or the length of a training block.
- Personal. Days until a wedding or a trip, or the length of time since an event.
Converting days into other units
| Days | Weeks | Hours | Approx. months |
|---|---|---|---|
| 30 | 4.3 | 720 | 1 |
| 90 | 12.9 | 2,160 | 3 |
| 180 | 25.7 | 4,320 | 6 |
| 365 | 52.1 | 8,760 | 12 |
The calculator already shows weeks, hours and minutes; the time duration converter handles less common units. The weekday count excludes Saturdays and Sundays but not public holidays, which vary by country; subtract those yourself for a working-day figure. The day counter offers another view of the same span.
Common mistakes
- Reversing the dates. If the end date is earlier than the start date the result is negative. Swap them for a positive count.
- Expecting months to have a fixed length. “1 month” from 31 January lands on 28 February or 3 March depending on how you count; the calculator uses the actual calendar, so the day total is the figure to rely on for contracts.
- Time zones. Dates are interpreted in your browser’s local time. Around midnight, a date entered in a different time zone can shift the count by one day.
- Two-digit years. Always enter a four-digit year to avoid a century mix-up.
Related tools
The hours calculator and time calculator add and subtract times within a day. The year of birth calculator works backwards from an age. For dates in different time zones, see the time zone converter, and for programmers the Unix timestamp converter turns a day count into seconds since 1970.
External references
Frequently asked questions
Does the calculator count leap years?
Yes. The day count comes from real calendar dates, so 29 February is included whenever it falls inside the range.
How are the months counted?
Calendar months, not blocks of 30 days. From 15 March to 15 April is one month whether that stretch has 30 or 31 days, and any days left after the last whole month are listed separately.
Can I count business days?
The weekday figure counts Monday to Friday. Subtract public holidays that fall inside the span to get working days for your country.
How do I count days including both the start and end dates?
Tick “Include the end date”. Monday to Friday then gives 5 days instead of 4.
Does it work for dates before 1970?
Yes. Browsers handle dates well before 1970 and far into the future, so historical spans are fine.