Date & Time
Time zones, durations and timestamps.
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Age Calculator Calculate exact age in years, months, days and hours.
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Birthday Paradox Probability of a shared birthday in a group of n.
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Calendar Week Grid Render a month grid with ISO week numbers.
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Countdown Timer Live countdown to any future date and time.
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Cron Next-Fire Times Given a cron expression, list the next 10 fire times in UTC.
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Date Add / Subtract Add or subtract days, weeks, months or years from any date.
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Date Difference Calculator Difference between two dates in every common unit.
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Date Format Converter Parse any date input and format it with a custom pattern.
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Day of the Week Finder Find the day of the week, day of year and ISO week for any date.
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Discordian Calendar Convert a Gregorian date to the Discordian calendar (5-day week, 73-day seasons).
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DST Transition Lookup Find the next DST start/end for any IANA time zone.
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Duration Formatter Format seconds or milliseconds as readable durations.
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Easter Date Calculator Compute Western and Eastern Orthodox Easter for any year.
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Equation of Time Compute the equation-of-time correction and approximate solar noon for any date.
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Golden Hour Calculator Compute morning/evening golden and blue hour windows, plus civil/nautical/astronomical twilight.
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Half-Birthday Calculator Given a birthday, find its six-month-after date.
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Hebrew / Hijri / Persian Calendar Convert Gregorian dates to Hebrew, Hijri (Islamic) and Persian calendars.
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ICS RRULE Builder Build an iCalendar RRULE string from frequency, interval, count or until, and BYDAY.
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ISO 8601 Duration Parser Parse ISO 8601 duration strings into component parts.
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ISO 8601 Duration Parser & Builder Parse ISO 8601 durations (P3Y2M10DT2H30M15S) and build canonical strings from numeric inputs.
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ISO Week Number ISO 8601 week-of-year, day-of-year, and Monday-start week range.
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Julian Date Converter Astronomical Julian Date (and MJD) ↔ Gregorian UT.
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Maya Long Count Convert a Gregorian date to the Maya Long Count (baktun.katun.tun.winal.kin).
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Meeting Time-Zone Planner Find overlapping working hours across multiple time zones.
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Moon Phase Calculator Approximate moon age, fraction and phase for any date.
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Pomodoro Timer 25-minute focus sessions with short and long breaks.
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Recurring Event Calculator Generate recurring event dates from a start date and interval.
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Relative Time Formatter Turn two timestamps into a friendly relative time phrase.
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Roman Calendar Converter Convert a Gregorian date to Kalends / Nones / Ides notation and AUC year.
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Saved Cron Schedules Bookmark cron expressions with a description.
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Stardate Calculator Earth date ↔ Star Trek TNG-era stardate.
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Stopwatch Start / stop / lap stopwatch with millisecond precision.
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Sunrise / Sunset Calculator Compute sunrise, sunset and solar noon for any latitude / longitude / date.
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Time Until… Live countdown to any future date and time.
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Time Zone Converter Convert any date and time between time zones.
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Time Zone Overlap Heatmap Visualize overlapping working hours across multiple time zones as a 24-hour grid.
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Twilight Calculator Civil / nautical / astronomical twilight times for any date and location.
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Working Days Calculator Count business days (Mon–Fri) between two dates.
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World Clock Live current time in cities around the world.
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Year Progress How far we are through the current year, month and day in real time.
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Zodiac Finder Western and Chinese zodiac for any date.