How to use the date calculator
- Days between: pick a start and end date to get the number of days, weeks, months and years between them, plus the number of weekdays.
- Add / subtract: pick a date and add or subtract days, weeks, months, years or business days.
- Age: enter a date of birth to get the exact age in years, months and days, and how long until the next birthday.
- Days until: pick a date or an event such as Christmas to count the days remaining.
How dates are counted
By default the end date is not counted, so from Monday to Friday is 4 days. That matches how most people count durations and how spreadsheets subtract dates. Tick Include the end date when you need to count both days, such as for hotel nights versus days of a holiday, or the length of a contract.
Adding months keeps the same day of the month when it exists. When it does not, the result moves to the last day of the month: 31 January plus one month is 28 February (29 in a leap year). Business days skip Saturdays and Sundays but do not know about public holidays, which differ by country, so subtract those yourself.
Calculations use calendar dates in UTC, so daylight saving changes never add or lose an hour. Leap years follow the Gregorian rules. Everything runs in your browser.
How many days are there between two dates?
Choose Days between and enter both dates. The difference is shown in days, and also as weeks and as years, months and days.
How is age calculated?
Full years are counted from the birthday, then full months, then remaining days. Someone born on 29 February has a birthday on 28 February in non-leap years for this calculation.
What date is 90 days from today?
Choose Add / subtract, keep today's date, enter 90 days and read the result with its weekday.