Date Difference Calculator
Find the exact time between two dates in years, months and days – plus total days, weeks, weekdays and hours – or add and subtract days from any date.
- Years, months and days
- Add or subtract
- Weekdays count
- Hours and minutes
Calculated in your browser. Nothing is saved.
The end date is included, so one day has been added.
Days in each year
Milestones from the start date
How to use the date difference calculator
- Pick the two datesChoose a start and end date, or tap a shortcut such as “Days left this year”. Tick “Include times” to count hours and minutes too.
- Read the differenceSee the gap in years, months and days, plus total days, weeks, weekdays, hours and seconds – updated as you type.
- Or add and subtractSwitch to “Add / subtract” to find the date that is, for example, 90 days or 3 months and 2 weeks from any date.
Counting days the right way
Date differences trip people up because there are two common conventions. This calculator follows the standard one used by spreadsheets and most programming languages: the start date counts, the end date doesn’t. Tick Include the end date when you need both, for example for a hotel stay counted in days or a leave application.
| Example | Without end date | With end date |
|---|---|---|
| 1 Jan to 1 Jan | 0 days | 1 day |
| 1 Jan to 31 Jan | 30 days | 31 days |
| 1 Jan to 31 Dec (common year) | 364 days | 365 days |
| Monday to Friday | 4 days | 5 days |
Why “months” can be tricky
Months range from 28 to 31 days, so the same number of days can be a different number of months depending on when you start. The calculator counts whole calendar months first and then the leftover days, the same way you would count on a calendar. When adding months, a day that doesn’t exist in the target month – like 31 April – moves to the month’s last day.
Weeks, weekdays and ISO weeks
Weekdays exclude the weekend you choose, which is useful for delivery times and notice periods. ISO week numbers follow the international standard ISO 8601: weeks start on Monday, and week 1 is the week containing the year’s first Thursday – so 1 January can fall in week 52 or 53 of the previous year.
Frequently asked questions
How do I calculate the number of days between two dates?
Choose the start and end dates and the total appears straight away. By default the start date is counted and the end date isn’t – so Monday to Tuesday is 1 day. Tick “Include the end date” to count both, which adds one day.
How are months and years worked out?
The calculator counts whole calendar months first, then the remaining days. For example, 31 January to 1 March is 1 month and 1 day in a common year. Because months have different lengths, total months are shown as months plus days rather than as a decimal.
How many weekdays are between two dates?
The Weekdays tile counts days that aren’t weekend days. Choose your weekend – Saturday and Sunday, Friday and Saturday, or Sunday only. Public holidays aren’t removed; use the Working Days Calculator for that.
What date is 90 days from today?
Switch to “Add / subtract”, keep today as the start date and enter 90 in Days. The result shows the date, its weekday and its ISO week number. Tick “Business days” to skip weekends.
What happens when I add a month to 31 January?
February has no 31st, so the result moves to the last day of February – 28 February, or 29 February in a leap year. The calculator tells you when this happens.
Does it handle leap years and daylight saving time?
Yes. Leap years are included in every count and the result lists any 29 February in the range. When you include times, the hour total accounts for clock changes in your time zone.
Can I count backwards or use dates in the past?
Yes. Any dates from year 1 to 9999 work. If the end date is before the start date, the calculator still shows the difference and tells you the order is reversed.
Is the calculator free?
Yes, completely free with no sign-up. Everything is calculated in your browser and nothing is saved.
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