Date & Age Calculator
✓ Link copiedA fast, private date calculator with three tools in one. Measure the duration between any two dates as years, months, and days plus exact totals; add or subtract years, months, weeks, and days from a date to find a future or past day; or compute an exact age from a date of birth. The calendar math handles leap years and uneven month lengths correctly, so month-end and February 29 edge cases always come out right. Everything runs entirely in your browser — no dates are ever uploaded.
0 days
- Total days
- 0
- Total weeks
- 0 + 0 days
- Total months
- 0
How to use
Pick a calculator with the tabs at the top. In Duration, choose a start and end date to see the gap in years, months, and days along with total days, weeks, and months. In Add / Subtract, enter a starting date, choose Add or Subtract, and type any combination of years, months, weeks, and days to get the resulting date and its weekday. In Age, enter a date of birth (and optionally an 'age at' date) to see an exact age and total days lived. Use Copy to grab any result.
Frequently asked questions
- How are leap years and month lengths handled?
- All math is done on the calendar, not on a fixed 30-day month. Leap years follow the full Gregorian rule (divisible by 4, except centuries not divisible by 400), and months keep their real lengths. When adding months lands on a day that doesn't exist — like January 31 plus one month — the result is clamped to the last day of the target month (February 28 or 29).
- Why does the duration show both a breakdown and total days?
- The years/months/days breakdown is how people usually describe a span ('3 years, 2 months'), but it depends on calendar boundaries. The total days, weeks, and months give an unambiguous count that's useful for billing periods, deadlines, and precise comparisons. Both are shown so you can use whichever fits.
- How is age calculated?
- Age is the full calendar duration from the date of birth to the chosen date — by default today — expressed as completed years, months, and days. A year only counts once the birthday has passed, so the figure matches how age is reckoned in everyday life, including for leap-day birthdays. No data is sent anywhere; the calculation runs entirely in your browser.