Date calculator

Enter the start date and the end date. The calculator counts every day from the start date up to the end date, and shows the same span in weeks, in years, months and days, as weekdays and weekend days, and in hours, minutes and seconds. Tick Include the end date when both days should count, such as for days of leave.

It depends on what you are counting. From Monday to Friday is 4 days if you count the gaps between dates, which is how ages and deadlines work, and 5 days if both Monday and Friday count, which is how leave and event days are usually counted. The checkbox switches between the two.

Open the Age calculator tab and enter your date of birth. It shows your age in years, months and days, the total months, weeks, days and hours you have lived, the day of the week you were born on, and how many days are left until your next birthday.

Pick a date and, if you like, a time and a name. The countdown ticks down to that moment in your own time zone, and shows the calendar days and weekdays left. Holiday buttons fill in the next Christmas, Thanksgiving, Easter and others. The date is saved in the address, so you can bookmark or share the countdown.

The day of the month stays the same where it can. When the new month is shorter, the result is that month’s last day, so 31 January plus one month is 28 February, or 29 February in a leap year. Spreadsheet functions such as EDATE work the same way.

Yes. Every date is worked out on the Gregorian calendar, including 29 February in leap years. A year is a leap year when it divides by 4, except century years, which must divide by 400. So 2028 is a leap year, while 2100 is not.

Open the Week numbers tab. It shows the current ISO week and every week of the year with its Monday and Sunday dates, and you can copy the list as CSV. ISO weeks run Monday to Sunday, and week 1 is the week that contains the year’s first Thursday.

Days between dates shows weekdays, Monday to Friday, and Add or subtract has a business days field that skips Saturdays and Sundays. Neither takes public holidays off, because they differ by country and region. Our business days calculator handles other weekend patterns.