Date & Time Calculators

Find your exact age, count days or business days between dates, convert timestamps and time things.

11 tools · everything runs in your browser

Time Format Converter
Convert between 12-hour AM/PM, 24-hour and military time instantly.
Work Hours Calculator
Calculate shift hours, weekly timesheets, unpaid breaks, and overtime pay.
Age Calculator
Your exact age in years, months and days, plus your next birthday.
Date Difference Calculator
Days, weeks and months between two dates, or add time to a date.
Business Days Calculator
Count working days and hours between dates, minus weekends and holidays.
Online Stopwatch
A stopwatch with laps, and a countdown timer with an alarm.

All Date & Time tools

Age Calculator
Your exact age in years, months and days, plus your next birthday.
Business Days Calculator
Count working days and hours between dates, minus weekends and holidays.
Countdown Timer
Run several countdown timers with an alarm, or count down to a date.
Date Difference Calculator
Days, weeks and months between two dates, or add time to a date.
HIIT & Tabata Interval Timer
Work and rest intervals with tones: Tabata, HIIT, EMOM, boxing.
Online Stopwatch
A stopwatch with laps, and a countdown timer with an alarm.
Pomodoro Timer
25/5 focus and break cycles with a daily session counter.
Time Format Converter
Convert between 12-hour AM/PM, 24-hour and military time instantly.
Unix Timestamp Converter
Convert epoch timestamps to readable dates and back.
Work Hours Calculator
Calculate shift hours, weekly timesheets, unpaid breaks, and overtime pay.
World Clock & Meeting Planner
See the time in any city and find a meeting time across time zones.

About these tools

Date arithmetic is deceptively hard by hand — months vary between 28 and 31 days, leap years add a day every four years, and 'ten days from Monday' means different things depending on whether the count is inclusive. These calculators use real calendar arithmetic rather than a fixed 365-day year, so long spans do not drift.

Both calendar days and working days are reported where relevant, since contracts, notice periods, and project plans usually mean the latter even when they say the former.

Frequently asked questions

Do these calculators handle leap years?

Yes. They use real calendar arithmetic rather than a fixed 365-day year, so every 29 February in the range is counted. Estimating with 365 days per year drifts by roughly one day every four years.

Does the day count include both the start and end date?

The difference is exclusive by default — 1 March to 8 March is 7 days. Many contracts count both endpoints, in which case add one. Which convention applies depends on your document, not on the arithmetic.

Are public holidays excluded from business-day counts?

No, only weekends. Public holidays vary by country, state, and sometimes industry, so subtract those separately using your own calendar.

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