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
- Age Calculator Exact age in years, months and days
- 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?"
- 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
- Business Days Calculator Pick a start and end date to count the business days between them
- Time Duration Calculator Enter a start and end time to get the duration in hours and minutes, decimal hours and total minutes
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.