Date & Time
Ages, durations, work hours and time zone conversions.
Ages, durations, work hours and time zone conversions. Date arithmetic looks trivial and is not — months have different lengths, years occasionally have 366 days, and much of the world shifts its clocks twice a year.
These calculators handle those cases explicitly rather than approximating, which is why the answers sometimes differ from a quick mental estimate.
6 calculators in this category
Age Calculator
Calculate exact age in years, months, and days.
Date Difference Calculator
Calculate the exact duration between two dates.
Time Calculator
Add, subtract, and convert hours, minutes, and seconds.
Hours Calculator
Calculate work hours, total time, and pay per period.
Time Zone Converter
Convert date and time across 25 major world time zones.
Days Alive Calculator
Discover your total days, heartbeats, breaths, and upcoming milestone days.
Which calculator do I need?
Start from the job rather than the tool.
- Work out an exact age — Age Calculator
- Count the days between two dates — Date Difference Calculator
- Add or subtract a duration from a time — Time Calculator
- Total up worked hours and pay — Hours Calculator
- Find what time it is somewhere else — Time Zone Converter
- See how long you have been alive in days — Days Alive Calculator
What these calculators have in common
Assumptions worth knowing before you rely on any result here.
A month has no fixed length
Adding one month to 31 January has no single correct answer, and durations quoted in months are approximations unless the exact dates are given. Where precision matters, count days.
Leap years are counted, not averaged
A year is 365 days except when it is 366, and the rule skips century years not divisible by 400. These calculators walk the actual calendar rather than multiplying by 365.25, which is why totals can differ slightly from other tools.
Daylight saving breaks naive hour arithmetic
Two days a year are 23 or 25 hours long in regions that observe it. A shift spanning the changeover is not the length the clock suggests, and a meeting time converted without accounting for it can land an hour out.