Date & time calculators
Count days, find dates, measure durations and convert time zones accurately.
Age Calculator
Find exact age in years, months and days — plus a countdown to the next birthday.
Days Between Dates Calculator
Count the days, weeks and months between any two dates.
Add Days to Date Calculator
Add or subtract days, weeks, months or years to find a future or past date.
Business Days Calculator
Count working days between two dates, optionally skipping US federal holidays.
Time Duration Calculator
Find the hours and minutes between two times — including overnight shifts and breaks.
Day of the Week Calculator
Find which day of the week any date falls on — past or future.
Week Number Calculator
Find the ISO week number for any date and the dates that week covers.
Time Zone Converter
Convert a date and time between US and world time zones, with daylight saving built in.
Calendar math without the mistakes
Months have different lengths, leap years add a day, and weekends change deadlines. These tools handle all of that using your device's calendar, so you get exact answers for contract deadlines, ages, project schedules and travel plans.
- Find exact age or time since an event with the age calculator.
- Count days with the days between dates calculator or working days with the business days calculator.
- Project a deadline with the add days to date calculator.
- Add up hours with the time duration calculator, and plan calls with the time zone converter.
Frequently asked questions
Do the date calculators account for leap years?
Yes. They use your browser's built-in calendar, which includes leap years and the correct number of days in every month.