Date Difference Calculator
Find the exact time between two dates.
Date & Time
Date maths, durations, calendars & countdowns.
Add or Subtract Days
Shift a date by days, weeks, months or years.
Days Until a Date
Count down the days to any future date.
Business Days Calculator
Count working days between two dates.
Leap Year Checker
Check whether a year is a leap year.
Day of the Week Finder
Find which weekday any date falls on.
Age in Days Weeks Months
See any age as years, months, days, weeks and hours.
Calendar Generator
Build a printable month calendar for any year.
Chinese Zodiac Finder
Find your Chinese zodiac animal and element by year.
Countdown to New Year
Live ticking countdown to the next New Year.
Date Format Converter
Reformat any date into ISO, US, long and custom.
Days in Month
How many days are in any month, leap years included.
Hours Calculator
Add up the hours between two times, minus breaks.
ISO Week Date Converter
Convert dates to and from ISO 8601 week numbers.
Julian Date Converter
Convert calendar dates to Julian Dates and back.
Moon Phase Calculator
See the moon phase for any date.
Pregnancy Due Date Estimator
Estimate your due date and current week.
Quarter Finder
Find the calendar or fiscal quarter for any date.
Sleep Cycle Calculator
Find the best time to sleep or wake up.
Time Adder Subtractor
Add or subtract hours, minutes and seconds from a time.
Time Ago Formatter
Turn any date into "3 hours ago" or "in 2 days".
Time Duration Calculator
Find the elapsed time between two clock times.
Week Number Calculator
Find the ISO-8601 week number for any date.
Working Hours Calculator
Net hours worked from clock-in, clock-out and breaks.
Zodiac Sign Finder
Find your star sign and Chinese zodiac from a birthday.
About Date & Time
Date arithmetic without the off-by-one errors: calculate the exact difference between two dates, add or subtract days, weeks or months, count business days excluding weekends, find what day of the week any date falls on, check leap years, and count down the days to a deadline. There is also an age calculator, a time-zone converter for scheduling across offices, and Unix timestamp helpers. Everything computes locally in your browser as you type — no uploads, no accounts — and handles calendar quirks (month lengths, leap years, DST) correctly so you do not have to.