Date & Time

Add or subtract any number of days from a date to find the resulting date and weekday. Free date add/subtract days calculator.

Calculate exact age in years, months and days between a birth date and any date.

Count the working days (Monday to Friday) between two dates, excluding weekends. Free business days and weekday counter.

Find the calendar date N working days after or before a start date, skipping weekends (and optional holidays).

Calculate the exact difference between two dates in years, months, days, weeks and total days. Free online date duration calculator.

Convert between Minguo (Republic of China) years used in Taiwan and Western Gregorian years — ROC year = Gregorian − 1911.

Calculate the duration between two times in hours and minutes, including overnight spans. Free time difference calculator.

Convert Unix timestamps (epoch seconds) to a human-readable UTC and local date, and convert any date back to a Unix timestamp.

Find the ISO 8601 week number for any date, with the ISO week year and weekday. Free what-week-is-it calculator.

Convert between 12-hour AM/PM clock time and 24-hour military time format instantly.

Sum a list of hour:minute durations and optionally find the end time from a start clock time.

Live countdown showing days, hours, minutes and seconds remaining until any future date and time.

Convert one date into many formats: ISO 8601, US, European, long form, ordinal and Unix epoch.

Find what day of the week any date falls on. Free day-of-week calculator showing the weekday, day of year, ISO week number and leap-year status.

Find how many days are in any given month and year, with leap-year February handled automatically.

Count the number of days from today until any future date, plus the number of weeks remaining. Free countdown to a date calculator.

Count down the days until your next birthday and see the age you will turn.

Convert decimal hours to hours:minutes:seconds and back again for payroll and time tracking.

Check whether any year is a leap year using the Gregorian rule, see why, and list the next few leap years and the number of days in February.

Convert between 24-hour military time and 12-hour AM/PM clock time instantly.

Convert dates to and from the RFC 2822 / email header format like 'Tue, 27 Jun 2026 14:30:00 +0000'.

Calculate the duration between two clock times, with optional crossing of midnight.

Convert the time between any two cities or time zones, with a live world globe showing day and night. Pick two cities, enter a time, see the local time in the other.

Convert Unix epoch milliseconds to a human-readable date and time, and back, with second and millisecond precision.

Convert a UTC time to any local time zone offset and back using fixed UTC offsets from -12:00 to +14:00.

Calculate hours worked from clock-in and clock-out times minus breaks, in decimal hours and hours:minutes. Free timesheet hours calculator.

Add or subtract years, months, weeks, days, hours, minutes and seconds from any date and time.

See your exact age expressed in years, months, weeks, days, hours and minutes from any reference date.

Parse a 5-field cron expression, describe it in plain English, and compute the next several run times from a chosen start date.

Find which day of the year a date is (1-366) and how many days remain in the year.

Convert a Unix epoch timestamp to a readable date in UTC or any fixed time-zone offset, with full date-time breakdown.

Convert Excel/Sheets serial date numbers to calendar dates and back, including the 1900 and 1904 date systems.

Convert ISO 8601 durations like P1Y2M10DT2H30M to total seconds, minutes, hours and days, or build a duration string from components.

Convert between Gregorian dates and ISO 8601 week dates (YYYY-Www-D), including ISO week number and weekday.

Convert an ISO 8601 year and week number into the exact calendar dates of that week.

Convert between Gregorian calendar dates and the astronomical Julian Day Number (JDN) and Julian Date used in astronomy.

Calculate the exact number of minutes (and seconds and hours) between two dates and times.

Find the approximate moon phase, illumination percentage and lunar age for any date.

Convert between calendar dates and the ISO ordinal date format YYYY-DDD (year plus day-of-year number).

Solve for pace, speed, distance or time for running, cycling and walking, with unit conversion.

Determine the calendar quarter, fiscal quarter and fiscal year for any date with a custom fiscal start.

Find which meteorological/astronomical season a date falls in, by hemisphere, with progress through it.

Find ideal bedtimes or wake times based on 90-minute sleep cycles and time to fall asleep.

Compute sunrise, sunset and day length for any location and date using the NOAA solar formula.

Convert a past date and time into a human-friendly 'N units ago' phrase with a full breakdown.

Add daily clock-in/clock-out times with breaks to get total hours, overtime and gross pay.

Count how many Mondays, Fridays or any weekday fall between two dates (inclusive).

Find the number of full weeks and leftover days between two dates, plus the decimal week count.