Age Calculator
Find completed years, leftover months, and leftover days between a birth date and an as-of date. The civil calendar runs in your browser — nothing is uploaded.
1. Enter values
2. Result
From 2000-01-01 to 2026-09-05
26 years
8
4
3. Summary
How is it calculated?
We count completed years, leftover months, then leftover days on the civil calendar. The as-of date is the end of the span, not an extra birthday.
Common use cases
Official forms
Report age in years, months, and days the way a clerk would write it.
School enrollment
Check age on a first-day-of-school or cutoff date.
Travel and visas
See how old someone will be on a flight or interview date.
Benefits filing
Set as-of to a filing date instead of guessing from today.
Family records
Reconstruct age at a wedding, census, or historical event.
Future planning
Move the as-of date forward to plan a birthday or milestone.
Your data stays private
Birth dates are compared locally in your browser. Nothing is uploaded or stored on a server.
About age in years, months, and days
Legal age, school enrollment, and many benefits forms ask for age in completed years. That is not the same as dividing the number of days since birth by 365.25. A child born on 29 February is a year older on 1 March in a common year. This calculator uses the civil calendar on this device: it subtracts the birth date from the as-of date, borrowing days from the previous month when needed, then borrowing months from the year. The result is completed years, leftover months, and leftover days — the same breakdown a clerk would write on a paper form.
Leave the as-of date on today when you want current age. Change it to a future date to see how old someone will be on a wedding day, a visa interview, or the first day of school. Change it to a past date to reconstruct age at an event. The math never leaves this tab. We do not store birthdays, and we do not use a server-side “today” that could disagree with your local calendar.
Ages are not medical advice. Pediatric growth charts and actuarial tables use different conventions. If a form asks for age in years only, use the years figure and ignore leftover months. If it asks for exact age on a filing date, set as-of to that filing date rather than guessing from memory.
How to calculate age
Enter the birth date
Use the civil date of birth, not the hospital admission date, if those differ. ISO dates avoid month/day swaps.
Set the as-of date
Keep today for current age, or pick a specific filing, travel, or school date. The result updates as you change either field.
Read years, months, and days
Copy the full breakdown, or tap an example if you only need a sanity check. Calculate scrolls to the result on a small screen.
Keep the date on this device
The comparison runs in this tab. Close the page and the dates are gone. Nothing is sent to Toolora.
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Age Calculator FAQ
It subtracts the birth date from the as-of date on the civil calendar in your browser. If the day-of-month has not been reached yet, it borrows days from the previous month, then borrows months from the year if needed. The years figure is completed years, not days-since-birth divided by 365. A 29 February birthday becomes 1 March in a common year. Example: 2000-01-01 as of 2026-09-05 is 26 years, 8 months, and 4 days.
The tool refuses that pair instead of showing a negative age. Swap the fields or pick a later as-of date. Same-day birth and as-of is 0 years, 0 months, 0 days. Time of day is ignored; only calendar dates matter. Future as-of dates are allowed so you can see age on a wedding or visa date.
No. The two dates are compared locally in this tab. Nothing is uploaded or stored on a server. Close the page and the dates are gone. This is not medical or legal advice — use the years figure if a form only wants completed years.