Age Calculator
Calculate exact age in years, months, and days between two dates.
Enter a date of birth to calculate exact age in years, months, and days as of today — or set any target date to find age on a specific day. Totals in months, weeks, and days are shown too.
The calculation is calendar-correct, accounting for different month lengths and leap years.
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Formula
Exact age
target date − birth date
Counted in whole years, then remaining months, then remaining days — borrowing across months and years as needed.
Total days
(target − birth) ÷ 1 day
The full span as a number of days, from which total weeks are derived.
How to use the age calculator
- 1Enter the date of birth.
- 2Optionally change the target date (it defaults to today).
- 3Read the exact age and the totals; copy the result.
Examples
| Example | Input | Result |
|---|---|---|
| Birthday | born 2000-01-01, today 2020-01-01 | 20 years |
| Mid-month | 2000-01-15 → 2000-03-10 | 1 month, 24 days |
| Milestone | any DOB | total days & weeks shown |
How exact age is calculated
Age is the time from the birth date to the target date, expressed as whole years, then the leftover months, then the leftover days. If the day-of-month of the target is earlier than the birth day, the calculator borrows a month (using the actual number of days in the previous month); if the month is earlier, it borrows a year. This calendar-correct method is why your age in months and days isn't simply the total days divided by 30.
Leap years are handled automatically because the math works on real calendar dates, not fixed-length months.
Other ways to count
Alongside years/months/days, the calculator shows the total number of days and weeks lived — useful for milestones (your 10,000th day) or for any context where a single unit is easier to work with than years, months, and days combined.
Frequently asked questions
How is exact age calculated?
By counting whole years from the birth date to the target date, then the remaining months and days, borrowing across months and years using real calendar lengths.
Does it account for leap years?
Yes. The calculation uses actual calendar dates, so leap years and varying month lengths are handled automatically.
Can I find my age on a future or past date?
Yes. Change the target date to any date on or after the birth date to find the age on that day.
Is my date of birth private?
Completely. The calculation runs in your browser and nothing is uploaded or stored.
Embed this calculator
Add the Age Calculator to your own website — free. Copy and paste this snippet:
<iframe src="https://numvella.com/embed/age-calculator" width="100%" height="460" style="border:1px solid #e2e8f0;border-radius:12px" title="Age Calculator — Numvella" loading="lazy"></iframe>Related calculators
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