# Time & Geography calculators

> Time-zone conversion, Unix timestamps, distance and bearing between coordinates, sunrise and sunset, moon phase, Easter, Julian dates, countdowns.

12 calculators. HTML index: https://tttkmbb.com/time · JSON: https://tttkmbb.com/api/v1/calculators?category=time

- [Time Zone Converter](https://tttkmbb.com/time/time-zone-converter.md): Converts a wall-clock date and time from one IANA time zone to another using the tz database rules built into ICU, so the daylight-saving offsets in force on that date are applied automatically. Reports both UTC offsets, the UTC instant, the weekday and the day difference. Tool: `convert_time_zone`.
- [World Clock Calculator](https://tttkmbb.com/time/world-clock.md): Takes a reference date and time in one IANA time zone and lists the corresponding local date, time, weekday and UTC offset in each zone of a list, using the tz database rules built into ICU (daylight saving included). Tool: `calculate_world_clock`.
- [Unix Timestamp Converter](https://tttkmbb.com/time/unix-timestamp.md): Converts a Unix timestamp (seconds or milliseconds since 1970-01-01T00:00:00Z, auto-detected) to a UTC and local date-time, or an ISO 8601 date-time (with optional time, offset or IANA zone) to epoch seconds and milliseconds, plus weekday, day of year and ISO week. Tool: `convert_unix_timestamp`.
- [Haversine Distance Calculator](https://tttkmbb.com/time/haversine-distance.md): Computes the great-circle (as-the-crow-flies) distance between two points on a spherical Earth with the haversine formula, in kilometres, miles and nautical miles, together with the initial bearing, compass direction and the midpoint of the route. Tool: `calculate_haversine_distance`.
- [Compass Bearing Calculator](https://tttkmbb.com/time/compass-bearing.md): Computes the initial (forward) and final bearing of the great-circle route between two latitude/longitude points, the back bearing for the return trip, the matching 16-point compass directions and the distance. Tool: `calculate_compass_bearing`.
- [Coordinate Converter](https://tttkmbb.com/time/coordinate-converter.md): Parses a latitude and longitude given either as signed decimal degrees or as degrees-minutes-seconds text (with N/S/E/W letters, symbols, colons or spaces) and returns all three standard forms: decimal degrees, DMS and degrees with decimal minutes, with hemisphere letters. Tool: `convert_coordinates`.
- [Sunrise and Sunset Calculator](https://tttkmbb.com/time/sunrise-sunset.md): Computes sunrise, sunset, solar noon, day length and civil twilight for any date, latitude and longitude with the NOAA Solar Calculator algorithm (Meeus-based solar position, equation of time, zenith 90.833° for refraction and the solar disc), reported in an IANA time zone. Tool: `calculate_sunrise_sunset`.
- [Moon Phase Calculator](https://tttkmbb.com/time/moon-phase.md): Estimates the Moon's phase name, illuminated fraction and age (days since new moon) for a calendar date from the mean synodic month of 29.530588853 days counted from the new moon of 2000-01-06 18:14 UTC, plus the dates of the next new and full moons. Tool: `calculate_moon_phase`.
- [Easter Date Calculator](https://tttkmbb.com/time/easter-date.md): Computes the date of Western (Gregorian) Easter Sunday for any year with the Meeus/Jones/Butcher algorithm and derives Ash Wednesday, Palm Sunday, Good Friday, Ascension Day and Pentecost; also gives Orthodox Easter from the Julian computus converted to the Gregorian calendar. Tool: `calculate_easter_date`.
- [Julian Date Calculator](https://tttkmbb.com/time/julian-date.md): Converts a Gregorian calendar date and time (in UTC or an IANA zone) to the astronomical Julian Day Number, Julian Date (JD), Modified Julian Date (MJD), Truncated Julian Date, days since the J2000.0 epoch and Julian centuries, plus day of year and ISO week. Tool: `convert_julian_date`.
- [Retirement Countdown Calculator](https://tttkmbb.com/time/retirement-countdown.md): Computes the date on which a person reaches a chosen retirement age from their date of birth and counts the days, weeks, calendar months and Monday–Friday working days remaining from a reference date. Tool: `calculate_retirement_countdown`.
- [Anniversary Calculator](https://tttkmbb.com/time/anniversary.md): Counts completed years, months and days since a start date (wedding, job, founding), finds the next anniversary date and the days until it, and names the traditional anniversary gift material for that year. Tool: `calculate_anniversary`.