Age & date difference calculator
Your exact age, or the gap between any two dates.
How to use the age calculator
- Enter the From / birth date — type it or use your browser's date picker. That's the only required field.
- The To date is pre-filled with today, so your current age appears as soon as the birth date is set. Change it to measure to any other day, past or future.
- Order doesn't matter — if the dates are reversed, the calculator swaps them automatically.
- Read the headline result in years, months and days (e.g.
36y 0m 26d) — the exact calendar age official forms ask for. - Below it, the same gap is shown as total months, total weeks and total days, for forms and milestones that count in a single unit.
Common uses
- Work out an exact age for paperwork — visa applications, insurance quotes, school-enrollment cutoffs and pension forms often want age in completed years on a specific date.
- Count down to an event: today in one field, the wedding, retirement or deadline date in the other, and read off the days and weeks remaining.
- Track a baby's age in weeks and months — early milestones are quoted in weeks, and the totals row gives both without hand-counting.
- Measure any span between two dates: length of service for an HR letter, remaining warranty days, how long a tenancy ran, or days since you quit a habit.
Tips & limitations
- Calculators can disagree by a day near month ends, because "a month" is ambiguous (is Jan 31 → Feb 28 one month?). This tool borrows days from the month before the To date — a common convention, but not the only one.
- Total months counts completed months (leftover days are dropped) and total weeks counts completed 7-day weeks; only total days is exact.
- Born February 29? In non-leap years your age rolls over on March 1 — on Feb 28 it still shows 11 months and 30 days.
- Day counts are anchored to midnight and rounded, so a daylight-saving clock change never makes the total off by one.
- Nothing is remembered between visits — reload and the dates reset, with the To date back to today.
How it's built & why it's safe
The whole calculator is a page of vanilla JavaScript built on the native Date object. The years-months-days figure is calendar arithmetic — subtract the date parts, then borrow real month lengths when the days go negative — so leap years and 28/30/31-day months come out right. The day total divides the millisecond gap by 86,400,000 and rounds, which keeps daylight-saving shifts from skewing it. Everything runs in your browser: no server, no account, and the dates you enter are never stored or sent anywhere — confirm it with View Source.
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Frequently asked questions
How exactly is the years-months-days age worked out?
It subtracts the calendar parts directly — years, months, days — borrowing the length of the month before the To date when the days go negative, and 12 months from the years when needed. That mirrors real life: your age ticks over on your birthday, not after a fixed number of days.
Why does another age calculator show a slightly different answer?
The years and the total-day count should always agree, but months are 28 to 31 days long and tools borrow differently when the day count goes negative. Near the end of a month, answers can legitimately differ by a day.
Can I count down to a future date?
Yes — put today in one field and the future date in the other; order doesn't matter because reversed dates are swapped automatically. You get the wait in years, months and days plus exact week and day totals.
What happens with a February 29 birthday?
In leap years everything is normal. In common years this calculator rolls the year over on March 1 — on February 28 it still shows 11 months and 30 days.
Are leap years and daylight-saving time handled?
Yes. Month borrowing uses each month's real length, so February 29 counts in leap years, and day totals come from midnight-anchored dates with rounding, so a clock change never adds or drops a day.
Is my birth date stored or sent anywhere?
No — the math runs in your browser as you type, with no server call and no storage. Close the tab and the dates are gone.