Date & Time

Calculate exact age in years, months, days and hours.

Probability of a shared birthday in a group of n.

Render a month grid with ISO week numbers.

Approximate dates for the 24 jiéqì solar terms in a given year.

Live countdown to any future date and time.

Given a cron expression, list the next 10 fire times in UTC.

Add or subtract days, weeks, months or years from any date.

Difference between two dates in every common unit.

Parse any date input and format it with a custom pattern.

Find the overlapping window and shared days between two date ranges.

Find the day of the week, day of year and ISO week for any date.

Convert a Gregorian date to the Discordian calendar (5-day week, 73-day seasons).

Find the next DST start/end for any IANA time zone.

Sum a list of HH:MM:SS durations and show the total and average.

Format seconds or milliseconds as readable durations.

Compute Western and Eastern Orthodox Easter for any year.

Compute the equation-of-time correction and approximate solar noon for any date.

Find the fiscal year and quarter for a date given a fiscal-year start month.

Convert a Gregorian date to the French Republican (revolutionary) calendar.

Compute morning/evening golden and blue hour windows, plus civil/nautical/astronomical twilight.

Given a birthday, find its six-month-after date.

Convert Gregorian dates to Hebrew, Hijri (Islamic) and Persian calendars.

Build an iCalendar RRULE string from frequency, interval, count or until, and BYDAY.

Parse ISO 8601 duration strings into component parts.

Parse ISO 8601 durations (P3Y2M10DT2H30M15S) and build canonical strings from numeric inputs.

ISO 8601 week-of-year, day-of-year, and Monday-start week range.

Astronomical Julian Date (and MJD) ↔ Gregorian UT.

Convert a Gregorian date to the Maya Long Count (baktun.katun.tun.winal.kin).

Find overlapping working hours across multiple time zones.

Approximate moon age, fraction and phase for any date.

25-minute focus sessions with short and long breaks.

Compute national public holiday dates for a given country and year.

Generate recurring event dates from a start date and interval.

Turn two timestamps into a friendly relative time phrase.

Convert a Gregorian date to Kalends / Nones / Ides notation and AUC year.

Bookmark cron expressions with a description.

Add business hours or business days to a start time, skipping weekends, holidays and non-working hours.

Convert between SMPTE timecode and frame counts at any frame rate.

Earth date ↔ Star Trek TNG-era stardate.

Start / stop / lap stopwatch with millisecond precision.

Compute sunrise, sunset and solar noon for any latitude / longitude / date.

Live countdown to any future date and time.

Convert any date and time between time zones.

Visualize overlapping working hours across multiple time zones as a 24-hour grid.

Civil / nautical / astronomical twilight times for any date and location.

Count business days (Mon–Fri) between two dates.

Live current time in cities around the world.

How far we are through the current year, month and day in real time.

Western and Chinese zodiac for any date.