All tools
Every calculator and clock on the site, grouped by what you are trying to work out.
The tools fall into a few broad groups. Clocks tell you what the time is somewhere — right now, or at a moment you choose. Converters move a single instant between zones and notations. Calculators answer questions about spans of time: how long between two dates, which day of the week, how many working days. Timers count down or measure elapsed time. Astronomy covers sunrise, sunset, twilight and the moon.
All of them run entirely in your browser. Nothing you type is sent anywhere, and no account is needed. Time zone conversions use the IANA database your browser already carries, which means daylight saving is applied by rule rather than by a stored offset — so a date in October converts differently from the same wall-clock time in June, exactly as it should.
One caveat worth stating plainly: every tool reads the current time from your own device. If your device clock is wrong, so is everything derived from it. The clock check tool measures the difference against a network reference.
Time tools
- World Clock Live local time in as many cities as you need.
- Time Zone Converter Convert a time between cities, with daylight saving handled for you.
- Time Difference Calculator How many hours ahead or behind two places are, right now.
- Meeting Planner Find an hour that works across several time zones.
- Event Time Announcer Announce one moment in every attendee’s local time.
- UTC Time The UTC reference clock with ISO and Unix values.
- Time Zone Directory Abbreviations, offsets and current time for every major zone.
- Clock Accuracy Check See how far your device clock differs from server time.
- Day & Night Map Where the sun is up right now, with a 24-hour scrubber.
- Distance Between Cities Great-circle distance, bearing and rough travel times.
- Clock Change Dates When each time zone next moves its clocks, and by how much.
Date tools
- Calendar Monthly calendar with week numbers, holidays and notes.
- Year Calendar All twelve months on one printable page.
- Date Calculator Add or subtract days, weeks, months and years from a date.
- Date Difference Calculator Days, weeks, months and hours between two dates.
- Age Calculator Exact age in years, months, days — and the next birthday.
- Business Days Calculator Working days between dates, minus weekends and holidays.
- Week Number ISO week number for any date, plus a full-year table.
- Day of the Week What day any date falls on, past or future.
- Leap Year Calculator Check whether a year is a leap year, and why.
- Holiday Calendar Public holiday lists by country and year.
- Time Calculator Add or subtract hours and minutes from a date and time.
- Time Duration Calculator How long between two times, in hours, minutes and decimal hours.
- Timesheet Calculator Weekly work hours with breaks, overtime and decimal totals.
- Workdays Calculator Count forward or back a number of working days from a date.
Timers
- Countdown Timer Count down to any date and time, in any zone.
- Online Timer One or many timers with presets and an alarm.
- Stopwatch Precise stopwatch with laps and keyboard control.
- Alarm Clock Set an alarm for a clock time, with repeat days and a sound.
- New Year Countdown Time left until the new year, and who reaches it first.
- Pomodoro Timer Focus sessions with breaks, a counter and a daily log.
- Sleep Calculator Bedtimes and wake times aligned to whole sleep cycles.
Developer tools
Astronomy
- Sunrise & Sunset Sunrise, sunset, day length and twilight for a month.
- Moon Phases Current moon phase and the month’s principal phases.
- Golden Hour Calculator Golden and blue hour windows for photographers, by location.
- Moonrise & Moonset Moonrise, moonset, phase and illumination for a whole month.
- Seasons Calculator Equinox and solstice times for any year, in your time zone.