Date & Time
Age, duration, time zones · 14 calculators
14 calculators
Age Calculator
Years, months, days
OpenDate Difference
Days between two dates
OpenAdd / Subtract Days
Date arithmetic
OpenWorking Days
Business days between dates
OpenTime Zone Converter
Multiple zones
OpenTime Calculator
Add / subtract hh:mm
OpenTime Card / Timesheet
Weekly hours + OT
OpenHours Between Times
Duration
OpenDay of Week
Mon..Sun for a date
OpenDay Counter
Days between dates
OpenCountdown
Days/h/m to target
OpenStopwatch
Elapsed time formatter
OpenPomodoro Timer
Session + breaks total
OpenGestational Age
Weeks pregnant
Open
Frequently asked about the Date & Time
What date/time calculators are here?
14 calculators: age (years + months + days + total days/weeks), date difference, add/subtract days, working days (with custom holidays), time-zone converter (10 zones), time add/subtract (hh:mm), timesheet (weekly hours + overtime), hours between times, day-of-week for a date, day counter, countdown to a future date, stopwatch formatter, Pomodoro timer planner, and gestational age (LMP → weeks pregnant + due date).
Do calculators handle leap years correctly?
Yes — every date calculator uses the native JavaScript Date object which handles leap years (every 4, except century, except every 400). Feb 29 birthdays show 'next birthday' correctly.
How does the working-days calculator handle holidays?
Excludes weekends by default. Paste your country's or company's holidays (one per line, YYYY-MM-DD) and they're excluded too. The output shows working days, weekend days, and holiday days separately.
Is the time-zone converter DST-aware?
Yes. Uses the IANA tz database via the browser's `Intl.DateTimeFormat`. London shifts from GMT to BST in March; the converter follows the rule automatically.
Can I calculate age in months or weeks specifically?
Yes — the Age calculator outputs years, months, days, total months, total weeks, and total days simultaneously. It also shows your next birthday and the day-of-week you were born.
What's gestational age vs pregnancy due date?
Gestational age = weeks since LMP (last menstrual period). Due date = LMP + 280 days. Both calculators are separate so you can use whichever input you have.