Date Calculators
Age and date-difference tools, accurate to the day.
About these calculators
Fourteen date calculators handling the calendar's genuine traps: leap years, month-length variation, business-day exclusions and the anniversary edge cases where February 29th participants celebrate. Age is computed exactly — years, months and days — not approximated by day counts divided by 365.25, which drifts wrong twice a decade.
Date arithmetic runs entirely in your browser against the proleptic Gregorian calendar, the civil standard behind official records. Results distinguish inclusive from exclusive counting where the difference matters, such as tenancy day-counts and notice periods.
Choosing the right calculator
Age and milestones
Age and chronological-age give exact age in years-months-days plus next-birthday countdowns; birthday finds weekday births and upcoming milestones; age-difference compares two birthdates precisely, useful for eligibility checks with strict cutoffs.
Adding and subtracting time
Add-days and date-add-subtract project deadlines forward or back with month-end intelligence — adding one month to January 31st lands sensibly rather than breaking; business-days skips weekends (and optionally custom holidays) for contract and delivery windows.
Differences and planning
Date-difference and days-until measure spans inclusively or exclusively; day-of-week identifies any historical or future weekday; month and years break long spans into readable parts; anniversary and leap-year resolve their special cases explicitly rather than approximately.
Date calculators we stand behind
Age Calculator
Find your exact age in years, months and days from your date of birth — plus total days, weeks, hours, minutes and your next birthday countdown.
Date Add Subtract Calculator
Add or subtract days, weeks, months or years to any date, including business days, and see the resulting weekday. Free, instant and precise.
Date Difference Calculator
Count the exact days, weeks, months, years and business days between two dates, with hours and minutes too. Perfect for deadlines, leave and projects.
Years Calculator
Calculate whole and fractional years between two dates, plus months, days and total days. Ideal for tenure, age and service periods.
Business Days Calculator
Count working days between two dates (weekends excluded) or add business days to a date to plan deliveries and deadlines.
Also available (9) — work in progress, not yet indexed
These calculators work but are still being checked for accuracy and sourcing, so they are not in search yet. They are free to use.