Date and Time Calculators: Stopwatch, Countdown Timer, Time Zones and Durations
From timing an exam practice session to converting a meeting between time zones, these tools handle the date and time arithmetic that is easy to get wrong by hand. The stopwatch records laps, the countdown timer can announce the remaining time at intervals you choose, and the duration and time-zone calculators work out exact differences.
11 free date and time calculators
Stopwatch
Stopwatch with lap times, a fullscreen mode and keyboard shortcuts.
Open calculator →Countdown Timer
Countdown for exams and study sessions, with presets, an alarm and a fullscreen display.
Open calculator →Age Calculator
Work out an exact age in years, months and days.
Open calculator →Date Calculator
Add or subtract days, weeks, months or years to a date.
Open calculator →Time Calculator
Add or subtract hours, minutes and seconds to a clock time.
Open calculator →Hours Calculator
Hours worked between a start and end time, with an optional break.
Open calculator →Time Card Calculator
Weekly timesheet — clock in/out and break per day, totalled up (with optional pay).
Open calculator →Time Zone Calculator
Convert a date and time from one time zone to another.
Open calculator →Time Duration Calculator
Exact duration between two dates and times.
Open calculator →Day Counter
Count the total days, weekdays and weekend days between two dates.
Open calculator →Day of the Week Calculator
Find which day of the week any date falls on.
Open calculator →Frequently asked questions
Does the countdown timer keep working if I switch tabs?
Yes. It counts down to a fixed end time on your device's clock, so it stays accurate even when the browser slows a background tab.