Free Date and Time Tools
13 free tools — Calculators, timers, world clocks, and timezone tools
Date Calculator
Add or subtract years, months, weeks and days from any starting date. Shows day of week, day of year and ISO week number.
Days Between Dates
Calculate the exact number of days between two dates with inclusive or exclusive end date. Also shows weeks, months and business days.
Add or Subtract Days
Find the date that is N days before or after any starting date. Quick single-input version of the date calculator.
Countdown Timer
Live countdown to any future date and time. Shows days, hours, minutes and seconds remaining, with the tab title updating in real time.
Stopwatch
Browser-based stopwatch with start, stop, lap and reset. Shows elapsed time in HH:MM:SS.mmm with a lap-time list.
Pomodoro Timer
Configurable Pomodoro timer. Default 25-minute work and 5-minute break cycles with audio cue at each phase change.
World Clock
Live clock display for multiple cities and time zones. Compare UTC, New York, London, Paris, Mumbai, Tokyo, Sydney at a glance.
Timezone Converter
Convert a date and time from one IANA time zone to another. Shows the converted day of week and UTC offset for both zones.
Week Number Calculator
Find the ISO 8601 week number for any date plus US and Middle East conventions. Also shows day-of-year, quarter and weekday.
Work Days Calculator
Count business days between two dates, excluding weekends and (optionally) public holidays for the US, UK, India or Germany.
ISO 8601 Converter
Parse and format ISO 8601 date-time strings. See the local and UTC representations plus year/month/day/hour/minute/second components.
Pregnancy Due Date Calculator
Estimate a pregnancy due date from the last menstrual period, conception date or an ultrasound. Also shows gestational age and trimester.
Retirement Date Calculator
Estimate your retirement date from current age and target retirement age. Shows years, months and days remaining plus country presets.
About Date & Time
Date and time tools handle the calendar arithmetic and timing tasks that come up all the time: adding or subtracting days from a date, counting the days between two dates (calendar and business), calculating ISO 8601 week numbers, converting times between IANA time zones, and watching live countdowns to upcoming deadlines. Every tool runs entirely in your browser using the native Date object and Intl APIs, so the dates you enter never reach a server.
Project managers use the date calculator and work-days calculator for milestones and SLAs. Distributed teams reach for the world clock and timezone converter when scheduling across continents. Students and remote workers use the Pomodoro timer and stopwatch to chunk focused work. Developers parse and emit ISO 8601 strings to debug API timestamps. Expectant parents and people planning retirement use the dedicated calculators for personal milestones.
All 13 tools update results live, copy/share without a sign-up, and rely on the browser's own timezone database — so daylight-saving transitions are handled automatically. Nothing is logged or transmitted; close the tab and your inputs are gone.