Counting days, ages and timestamps
The tools here answer the questions you would otherwise work out on a calendar, counting on your fingers.
Between two dates. The days between dates calculator counts the days from one date to another, with or without the end date, and shows the same span in weeks, months and working days. Its second tab works the other way round: it adds or subtracts days, weeks or months and tells you which date you land on, for a deadline, a notice period or a delivery estimate.
Age. The age calculator gives the exact age in years, months and days on any date, the next birthday, round milestones like the 10,000th day, the age in Hijri years and the age difference between two people.
Time as a number. The Unix timestamp converter turns the seconds since 1 January 1970 that computers store into a readable date and back. The time converter converts seconds, minutes, hours, days, weeks and years into each other.
What they all do the same way
Your dates stay in the browser. Nothing is uploaded. A date of birth is never written into the address bar, and it is remembered only if you ask for it.
A day is a calendar day. The date tools count whole days in the Gregorian calendar, without time zones, so a change to or from daylight saving time never adds or removes an hour.
Results you can take with you. Each value has its own copy button, and dates can go straight into Google Calendar, Outlook or Apple Calendar as an .ics file.