Age Calculator
Enter a date of birth to see the exact age in years, months, and days, updated instantly as you type.
Options
Processed on your device — nothing is sent anywhere.
How it works
- Enter the date of birth in the date field.
- Optionally open Options to change the reference date from today to any other day.
- Read the exact age in years, months and days, along with total days lived and the countdown to the next birthday.
Frequently asked questions
- How is the age in years, months and days calculated?
- The calculator counts full calendar years first, then full calendar months, then the remaining days. Because months have different lengths, this is the same method used for official purposes, so the result matches what forms and institutions expect.
- Can I calculate age at a date other than today?
- Yes. Open the Options section and set the reference date to any day, past or future. The result then shows the age as of that date, which is useful for filling in forms or checking eligibility at a deadline.
- Is my date of birth sent to a server?
- No. Every calculation happens locally in your browser and nothing is transmitted or stored anywhere. You can even load the page and then go offline before entering any dates.
- How does the calculator handle leap year birthdays on February 29?
- A person born on February 29 completes a year of age on March 1 in non-leap years, which is the convention most jurisdictions use, and the calculator follows it. The next-birthday countdown points to February 29 when the coming year is a leap year and to March 1 otherwise.
- Why do total days lived and the year count seem to disagree?
- They measure the same span two ways. Years, months, and days follow the calendar, so a month can be 28 to 31 days long, while total days is a plain count of days between the two dates. Multiplying age in years by 365 will therefore land a few days off, because leap days and varying month lengths only show up in the exact day count.
About this tool
This age calculator turns a date of birth into an exact age: full years, remaining months, and remaining days, plus the total number of days lived and a countdown to the next birthday. It answers the questions people actually search for — how old someone is today, how old they were on a specific date, or how many days remain until a birthday — with one input and no signup.
The calculation follows calendar arithmetic rather than dividing by 365.25. Full calendar years are counted first, then full calendar months, then leftover days, which is how ages are determined for legal forms, school enrollment, visas, and pension eligibility. Leap years are handled correctly, including the February 29 edge case, and the optional reference date lets you compute an age as of any day in the past or future — useful for checking whether someone met an age requirement on a contest deadline or an application cutoff.
Everything runs client-side in your browser with plain JavaScript date arithmetic. The date of birth is never transmitted, logged, or stored on any server, which matters because a birth date is personal data often used in identity verification. Once the page has loaded you can disconnect from the internet entirely and the calculator keeps working.
Beyond the obvious use, the exact day count has practical value of its own: it is the number insurers, some airlines, and medical dosing charts care about for infants, and it lets you find milestone dates such as a 10,000th day. If you need an age at a moment other than now, set the reference date first and then enter the birth date — the result updates live with every keystroke.