Date Calculators
Work out the gap between dates, add or subtract time, and count working days.
Date & Time Tools
Free tools for calculating, converting and working with dates and times.
Calculated in your browser. Nothing you enter is sent to a server.
Tool categories
Time Tools
Count down to a moment and convert between units of time.
Calendar Tools
Browse calendars, look up week numbers, and check month and year lengths.
Date Converters
Change dates between formats, day numbers and Unix timestamps.
Time Zone Tools
Convert times between places and keep an eye on clocks around the world.
Why use DateUtils?
Answers you can check
Every page says exactly how its calculation works: whether the end date counts, what happens at the end of a month, how leap years and daylight saving are treated.
Private by design
Calculations run in your browser. There are no accounts, and the dates, birthdays and time zones you enter are never sent to a server.
Fast and plain
Each tool has its own address, loads quickly on a phone and works with a keyboard and screen reader. Results can be copied or printed.
Browse all tools
Date Difference Calculate the exact difference between two dates in days, weeks, months and years. Add or Subtract Days Add or subtract days, weeks, months or years from any date. Age Calculator Find exact age in years, months and days from a date of birth. Countdown See how many days, hours, minutes and seconds remain until a date and time. Business Days Count the working days between two dates, excluding weekends and holidays you choose. Add Business Days Find the date that falls a set number of working days from a start date. Day of the Week Find out which day of the week any date falls on. Week Number Find the ISO 8601 week number and week-year for any date. Leap Year Check whether a year is a leap year and find the previous and next leap years. Days in a Year Find out whether a year has 365 or 366 days. Days in a Month Look up how many days a month has in any year. Calendar Browse a clean calendar for any month and year, with week numbers. Date Formatter Show a date in common formats and copy the one you need. Unix Timestamp Convert Unix timestamps to dates and dates to Unix timestamps. Time Zone Converter Convert a date and time from one time zone to another. World Clock Follow the current time in cities around the world. Time Converter Convert between seconds, minutes, hours, days and weeks. Date to Day Number Convert a date to its day number in the year, or a day number back to a date. Quarter Calculator Find which calendar quarter a date is in, and when it starts and ends. Start and End of Period Find the first and last day of the week, month, quarter or year containing a date.
Date and time calculators that show their working
Most date questions sound simple until the details matter. "How many days between these dates?" depends on whether you count the first day. "What is one month after 31 January?" has no obvious answer. "What time is it in Sydney when it is noon in Dublin?" changes twice a year, and not always on the same weekend for both places.
DateUtils gives a clear result first and the reasoning next. Start with the date difference calculator to count days between two dates, the business days calculator to count working days, or the time zone converter to plan across regions. Developers can use the Unix timestamp converter and the date format converter to check values quickly.
The tools are grouped into date calculators, time tools, calendar tools, date converters and time zone tools. New tools are added only when they answer a real question well.