Date Calculators
Calculate exact ages, count days between dates, add or subtract calendar time, and plan deadlines without leaving the browser.
Date, age, and days-between tools
These date tools answer common calendar questions quickly: how old someone is, how many days remain until a deadline, how many business days a project has, what date lands after adding months, weeks, days, and workdays, or what time a meeting lands in another time zone.
Each calculator makes the assumptions visible, including inclusive end-date counting, weekend and holiday exclusion, leap-day birthdays, timestamp units, time zone offsets, and month-end rollover rules.
Choose the right date tool
- Age Calculator: exact age in years, months, and days, plus days lived, next birthday, weekday born, zodiac, generation, and milestones.
- Days Between Dates Calculator: calendar days, business days, weekends, full weeks, approximate months, and a monthly breakdown.
- Date Calculator: add or subtract years, months, weeks, days, and business days with explicit month-end behavior.
- Time Zone Converter: convert a wall-clock time between IANA time zones with UTC, offsets, weekday changes, and day-shift details.
- World Clock: keep live clocks for multiple time zones with GMT offsets, dates, home-zone comparison, and work-hours status.
- Unix Timestamp Converter: convert seconds, milliseconds, microseconds, and nanoseconds to dates and back again.
- Business Days Calculator: count workdays or add and subtract business days with configurable weekends and custom holidays.
Available tools
7 results
Useful date calculations for planning
Dates get tricky around weekends, leap years, short months, daylight-saving changes, timestamp units, and deadlines that include the final day. Use calendar days for countdowns, business days for work schedules, exact age for eligibility checks, time zone tools for meetings, and date addition for payment terms, renewals, follow-ups, and milestones.
Common date calculator questions
What is the difference between calendar days and business days?
Calendar days count every date in the range. Business days exclude Saturdays and Sundays, which is useful for work deadlines, shipping estimates, and payment terms.
Should I include the end date when counting days?
Use inclusive counting when the final date itself should count, such as event spans, memberships, or nights stayed. Leave it off for elapsed time from one date to another.
Why do month calculations need a month-end rule?
Adding one month to January 31 can clamp to February 28 or roll into March depending on the rule. The Date Calculator lets you choose the behavior.
How are leap-day birthdays handled?
The Age Calculator lets you decide whether February 29 birthdays use February 28 or March 1 in non-leap years.