Calendar Reference

Age on Other Planets Calculator

Convert an Earth age or birthdate into Mercury, Venus, Mars, Jupiter, Saturn, Uranus, and Neptune years, with orbital periods.

Chinese New Year Calculator

Find the Chinese New Year date for any supported year, compare nearby Lunar New Year dates, and review the zodiac animal, element, yin-yang polarity.

Christmas Countdown Calculator

See how many days, weeks, sleeps, weekdays, hours, and minutes remain until Christmas Day, with weekends, Fridays, Christmas Eve.

Date Countdown Calculator

Use this countdown calculator to see days until any date or days since a past one, with calendar-aware years, months, weeks plus days, planning checkpoints.

Day Length Calculator

Use this day length calculator to estimate daylight hours by date and location, compare seasonal daylight change.

Day of Week Calculator

Find the day of the week for any valid Gregorian date, plus ISO day number, day of year, ISO week, birthday weekday lookups, weekend status.

Days in Month Calculator

Find how many days are in any month and year, including leap-year February rules, 30-day and 31-day month tables, weekday/weekend counts.

Days in Year Calculator

Use the days in a year calculator to check whether any year has 365 days or 366 days, understand the leap-year rule, compare century-year examples.

Easter Date Calculator

Use this Easter date calculator to find when Easter Sunday falls, compare Western and Orthodox Easter, review Holy Week dates, and scan nearby years.

Golden Hour Calculator

Use this golden hour calculator to estimate golden hour and blue hour times for photography by date and location, with morning and evening planning windows.

Leap Year Calculator

Use this leap year calculator to check whether any year has 365 or 366 days, understand why 2000 was a leap year but 2100 will not be.

Moon Phase Calculator

Use the moon phase calculator to check the lunar phase, moon age, illumination percentage, and next major lunar milestones for any date.

Sunrise & Sunset Calculator

Use the sunrise sunset calculator to estimate sunrise, sunset, solar noon, day length, and civil, nautical, and astronomical twilight times for any latitude.

Week Number Calculator

Use the week number calculator to find the ISO week number for any date, convert an ISO week number back into dates, see the Monday and Sunday for that week.

Weekdays in Year Calculator

Count how many weekdays in a year fall on Monday through Friday, compare them with weekend totals.