Age Calculator
Find an exact age in years, months, days, hours and the next birthday countdown.
Calculate an Exact Age in Years, Months and Days
Working out an age from a date of birth sounds trivial until leap years and uneven month lengths get involved. Subtracting years alone is wrong whenever the birthday has not yet happened this year, and treating a month as thirty days drifts by days over a lifetime.
This calculator does the calendar arithmetic properly: it borrows days from the actual preceding month rather than an average, so the answer matches how a person would count it. You also get the total in days, weeks and hours, the weekday you were born on, and a countdown to the next birthday.
Key features
- Calendar-accurate — leap years and real month lengths are respected, not approximated.
- Age on any date — not just today, so you can find an age as of a deadline, an anniversary or a historical event.
- Totals in every unit — days, weeks, months and hours lived.
- Birthday countdown — exact days until the next one, and the weekday of the original birth date.
This tool runs entirely inside your browser using native Web APIs. Your files and text are never uploaded to a server, never logged and never shared with third parties.
How to use: Age Calculator
- Enter the date of birth
Use the date picker or type the date directly in your browser’s format. - Choose the date to measure against
It defaults to today. Change it to calculate an age at a future or past date — useful for eligibility cut-offs. - Read the breakdown
The three cards show completed years, months and days. The table underneath gives the same span in other units. - Check the birthday countdown
The table shows how many days remain until the next birthday from the measurement date.
Technical specifications
| Processing location | Entirely in your browser — no server round trip |
|---|---|
| Data uploaded | None. Files and text never leave your device |
| Price | Free — no account, no trial, no usage cap |
| Category | Calculators |
| Works offline | Yes, once the page has loaded |
| Browser support | Chrome 90+, Edge 90+, Firefox 90+, Safari 15+ |
| Interface languages | English, 中文, हिन्दी, Español, العربية |
Frequently asked questions
How is age calculated exactly?
Completed years are counted first, then whole months, then leftover days — borrowing from the real length of the preceding month when needed. This is how chronological age is defined legally and medically in most countries.
Does it handle leap years and 29 February birthdays?
Yes. Day counts come from real calendar dates rather than a fixed year length. A 29 February birthday is treated as falling on 1 March in common years, which is the most widely used convention.
Why does my age in months not equal years times twelve plus months?
It does — the table shows total completed months, which is exactly years × 12 + months. The day remainder is listed separately because months have unequal lengths.
Is my date of birth sent anywhere?
No. The calculation runs in JavaScript inside your browser. A date of birth is sensitive personal data, and this tool never transmits, stores or logs it.