Date & Time Tools
Timestamps, ages, durations, deadlines and timezones, computed with the browser's own calendar and IANA timezone engines, so leap years and daylight saving are handled the way your operating system handles them. Nothing you enter leaves your device.
- Unix Timestamp Converter Epoch to date and back, paste 1720224000 or 1720224000000, get the human-readable moment in your timezone and UTC instantly.
- Age Calculator Exact age in years, months and days, plus total days lived and a countdown to the next birthday.
- Days Between Dates Calculator Pick two dates, get the gap four ways: total days, weekdays only, complete weeks, and the calendar years-months-days breakdown.
- Date Add / Subtract Calculator "What date is 90 days from today?", pick a start date, add or subtract days, weeks, months or years, and see the result with its weekday.
- Week Number Calculator Any date → its ISO 8601 week number, with the week's exact Monday, Sunday range. Today's week number shown by default.
- Time Zone Converter 9:00 in New York is what time in Kathmandu? Pick a time and two zones, DST rules applied automatically from the browser's own timezone database.
- Business Days Calculator Pick a start and end date to count the business days between them, weekends excluded, with an option to subtract public holidays.
- Time Duration Calculator Enter a start and end time to get the duration in hours and minutes, decimal hours and total minutes, with a break deduction.
- Day of the Year Calculator Enter a date to get its day-of-year number (Jan 1 = 1), how many days are left in the year, and how much of the year has passed.
- Day of the Week Calculator Enter any date and instantly see which day of the week it is (or was), whether it’s a weekend, and how many days from today.
- Add Business Days Calculator Pick a start date and a number of business days to add (or subtract), the tool skips Saturdays and Sundays and gives the resulting date.
Dates and time zones, without the traps
Time is deceptively tricky: Unix timestamps, ISO strings, leap years, and the ever-present time-zone and daylight-saving pitfalls that cause off-by-an-hour bugs and missed meetings. These tools convert timestamps, do date arithmetic (add or subtract days, find the gap between two dates, work out an exact age), and compare times across zones, using your device's own time-zone database.
Everything is computed locally in your browser, so a birthdate or a deadline you enter isn't sent anywhere. For converting between world calendar systems, Hijri, Hebrew, Persian, Julian and more, see the Calendars category.
Frequently asked questions
Are these calculations accurate across leap years and DST?
Yes, everything runs on the browser's own calendar and timezone engines: leap days come from real calendar arithmetic, and timezone conversions use the IANA database your operating system also uses, so daylight-saving transitions are applied automatically.
Why run date tools client-side?
Dates are quietly personal, birthdates, deadlines, medical appointments, contract dates. There is no reason a subtraction between two dates should travel to a server. Here it never does; the tools even work offline.
Do the tools use my computer's timezone?
Local-time displays use your device's timezone setting, and UTC is shown alongside where it matters (timestamps). The timezone converter lets you pick both zones explicitly.