Date & Time calculators
Free online calculators to add or subtract days, count weekdays, figure out age, due dates, or how long until an event.
Dates are surprisingly awkward. These tools take the guessing out.
Popular in Date & Time
- Age Calculator
Calculate exact age in years, months, and days from a date of birth, with total days, total weeks, and days until your next birthday.
- Date Difference Calculator
Count the exact number of days, weeks, months, business days, hours, and minutes between any two dates.
- Time Duration Calculator
Calculate the exact elapsed time between two dates and times in years, months, days, hours, minutes, and seconds.
- Countdown Calculator
Live countdown to any future date and time, updated every second, showing days, hours, minutes, and seconds remaining.
- Days Until Holiday Calculator
See how many days until every major US and international holiday, all on one page. Updates automatically based on today's date or any reference date you choose.
All date & time calculators
- Add or Subtract Days Calculator
Add or subtract any number of days from a starting date and instantly see the resulting date and day of the week.
- Age Calculator
Calculate exact age in years, months, and days from a date of birth, with total days, total weeks, and days until your next birthday.
- Business Days Calculator
Count the number of business days (Monday–Friday) between two dates, alongside calendar days and weekend days.
- Countdown Calculator
Live countdown to any future date and time, updated every second, showing days, hours, minutes, and seconds remaining.
- Date Difference Calculator
Count the exact number of days, weeks, months, business days, hours, and minutes between any two dates.
- Daylight Duration Calculator
Calculate daylight hours for any latitude across a full year or a custom date range. See monthly averages, the longest and shortest days, and solstice and equinox dates.
- Days Until Holiday Calculator
See how many days until every major US and international holiday, all on one page. Updates automatically based on today's date or any reference date you choose.
- Hours Calculator
Add up timesheet hours and minutes across multiple shifts, subtract breaks, and get the total in hours and decimal format.
- Julian Date Converter
Convert between Gregorian calendar dates and Julian Day Numbers (JDN). Also computes the Julian Date, Modified Julian Date, and J2000 epoch offset used in astronomy.
- Moon Phase Calculator
Find the moon phase for any date — new moon, full moon, or anything in between. Shows phase name, illumination percentage, and the dates of the next new and full moons.
- Sunrise and Sunset Calculator
Find the exact sunrise, solar noon, and sunset times for any date and location. Also shows civil and astronomical twilight, day length, and polar day or night conditions.
- Time Adder and Subtractor
Add or subtract days, hours, minutes, and seconds from any date and time. Get the exact result date and time instantly. Uses UTC internally so the result is always correct regardless of daylight saving time.
- Time Duration Calculator
Calculate the exact elapsed time between two dates and times in years, months, days, hours, minutes, and seconds.
- Time Zone Converter
Convert a time from one world time zone to another. Supports 18 common zones including US, Europe, Asia, and Pacific.
- Unix Timestamp Calculator
Convert a Unix timestamp to a human-readable date and time, or convert any date and time to its Unix timestamp in seconds and milliseconds.
- Week Number Calculator
Find the ISO and US week number for any date, plus day of year, day of week, quarter, and weeks remaining in the year.
- Weekday Calculator
Find the day of the week, day of the year, ISO week number, and whether a date is a weekend or falls in a leap year.