How to use the date difference calculator
- Pick a start date and an end date. They open pre-filled with today and thirty days from now so you can see how it works.
- Decide whether the end date counts. Tick Include the end date for situations like hotel nights versus days on site, or a contract that covers both the first and last day.
- Read the answer as total days, as years-months-days, as weeks and days, and as a split of weekdays and weekend days. If the dates are the wrong way round the tool swaps them for you and tells you it did.
Use the working days calculator when public holidays matter, and the add or subtract days tool when you know the number of days and need the date.
How the count works
days = (end date − start date) in whole days, + 1 if the end date is included
Both dates are treated as calendar days with no time of day, so daylight-saving changes cannot add or remove an hour from the answer. The "years, months, days" line is separate: it uses the same calendar method as the age calculator, counting whole months forward from the start date and then the leftover days.
Weekdays are counted by working through full weeks (five weekdays each) and then checking the leftover days one by one, starting from the real day of the week of the start date. Public holidays are not removed.
Worked example
How many days are there from 1 January 2025 to 1 March 2025?
- January has 31 days and February 2025 has 28, so the gap is 31 + 28 = 59 days.
- In years, months and days that is 0 years, 2 months, 0 days.
- That is 8 weeks and 3 days. Starting on a Wednesday, the 59 days contain 43 weekdays and 16 weekend days.
- If both the first and last day count, as in "from 1 January to 1 March inclusive", the answer is 60 days.
The two-day difference between "between" and "inclusive" is the most common source of disagreement over deadlines, so the tool shows the option instead of hiding it.
Inclusive versus exclusive counting
| Situation | Count the end date? | Example 10–15 June |
|---|---|---|
| Time elapsed, age, days since an event | No | 5 days |
| Hotel nights, car hire days | No (you leave on the last day) | 5 nights |
| Days on site, conference days, leave taken | Yes | 6 days |
| A contract running “from 10 June to 15 June” | Usually yes: check the wording | 6 days |
When a legal or financial document depends on the answer, rely on the document's own wording. Some contracts and statutes say a period starts on the day after the event, so the exact rule matters.
Useful reference spans
| Span | Days | Notes |
|---|---|---|
| One common year | 365 | 52 weeks and 1 day |
| One leap year | 366 | Years divisible by 4, except most century years |
| One week | 7 | 5 weekdays and 2 weekend days |
| 30 days | 30 | Roughly one month, used in many notice periods |
| 90 days | 90 | Common trial period and quarter length |
| 180 days | 180 | About six months |
| Four years | 1,461 | Includes one leap day |
| 400 years | 146,097 | The full Gregorian leap-year cycle, exactly 20,871 weeks |
Notice periods, trial periods and warranty windows are often written in days, not months, to avoid disputes about month lengths. If a document says "within 30 days of the invoice date", count the invoice date as day zero unless the wording says otherwise, and paste the two dates here to find the due date by checking the result. For the reverse job, where you know the start and the number of days, the add or subtract days tool gives the date directly.
Accuracy and limits
Dates use the proleptic Gregorian calendar, which is today's calendar extended backwards. The "months (approx.)" figure divides the day count by the average month length of 30.4369 days and is only a guide; use the years-months-days line for a calendar-exact answer. Public holidays and local rest days are never excluded.
Frequently asked questions
How many days are between two dates?
Subtract the earlier date from the later one in whole days. For example, 1 January to 1 March 2025 is 59 days, or 60 if you count both the first and last day.
Does the calculator include the end date?
Not by default, which matches the usual meaning of days between. Tick the include option to count both ends, which is what you want for leave, events and many contracts.
Does it handle leap years?
Yes. February has 29 days in 2024 and 2028, and the calculation uses the true calendar, so a span that crosses 29 February gains one day.
Can I count weekdays only?
The result shows weekdays (Monday to Friday) and weekend days separately. For a count that also removes public holidays, use the working days calculator.
What happens if the start date is after the end date?
The tool swaps them and tells you so, because the gap between two dates is the same either way.