Age Calculator
Calculate your exact age in years, months and days from a date of birth — using real calendar arithmetic, not a rough estimate.
No uploads • No tracking • No registration
How It Works
Enter your date of birth
Pick the date from the calendar or type it directly.
Choose a target date
Defaults to today, but you can calculate age on any past or future date.
Read the exact breakdown
See years, months and days, plus totals and your next birthday countdown, instantly.
Privacy note: everything happens locally in your browser. Your date of birth is never sent to a server, stored or logged.
How the calculation works
This calculator does not divide total days by 365. It compares your birth year, month and day against the target date directly: it subtracts days, borrowing the number of days in the previous calendar month whenever the target's day-of-month is smaller than your birth day-of-month, then subtracts months, borrowing a year when needed. That's exactly how you'd count age by hand on a calendar, which is why it stays accurate across leap years and months of different lengths.
Frequently Asked Questions
How is exact age calculated?+
This tool uses calendar arithmetic, not a simple days-divided-by-365 estimate. It compares the year, month and day of your date of birth against the target date, borrowing days from the previous month when needed, so leap years and different month lengths are handled correctly.
What happens if I was born on February 29?+
In non-leap years, February 29 doesn't exist, so your calendar anniversary is treated as March 1, consistent with how JavaScript's own date arithmetic rolls over. In leap years, February 29 is used normally.
Can I calculate my age on a future or past date instead of today?+
Yes. Use the "Calculate age on" field to pick any date, past or future, and every result updates for that date instead of today.
Why does the total months figure differ from years times twelve?+
Total months here means the full calendar months elapsed (years × 12 plus the extra whole months), not an approximation from total days. It intentionally excludes the leftover days shown separately.
Is the total seconds figure exact?+
It's labelled approximate because it's derived from full calendar days (86,400 seconds each) and does not account for the specific time of day you were born, which this tool doesn't ask for.
Does this tool store or send my date of birth anywhere?+
No. All calculations run locally in your browser using JavaScript. Nothing you enter is uploaded, logged or stored.
Can I find out what day of the week I was born on?+
Yes. Once you enter a date of birth, the tool shows the day of the week it fell on, calculated directly from the calendar.
What if I enter a date of birth that's after the target date?+
The tool shows a validation message instead of a nonsensical negative age. Make sure the date of birth is on or before the date you're calculating age on.