How to use the Age Calculator
- Enter the date of birth. Use the date picker or type the date in your device's date format.
- Check the "age on" date. It is set to today automatically. Change it to find someone's age on a past or future date — for example, on the day an application closes.
- Read the results: the exact age in years, months and days, the totals in months, weeks and days, and a countdown to the next birthday.
What this tool does
Working out an age sounds trivial until you need it to the day. Forms for school admissions, sports categories, visas, insurance and pensions often ask whether someone has reached a certain age on a specific date, and a mistake of one day can matter. The Age Calculator counts full calendar years and months, then the remaining days, the same way people naturally describe age: "34 years, 5 months and 12 days".
How the age is calculated
The calculator does not divide days by 365. Instead it steps through the calendar:
- Count the number of complete years between the birth date and the target date. A year is complete once the birthday has been reached.
- From the last birthday, count the number of complete months.
- Count the remaining days from that month anniversary to the target date.
The totals are exact calendar counts too: total days is the number of days between the two dates (leap days included), and total weeks is that number divided by seven and rounded down.
Month-end and leap-year birthdays
Months have different lengths, so some dates need a rule. When a month anniversary does not exist — for example, one month after 31 January — the calculator uses the last day of that month (28 or 29 February). People born on 29 February are treated as reaching their birthday on 28 February in non-leap years, which matches the rule used for legal ages in many places. Some jurisdictions use 1 March instead, so check the rules that apply to you when the date matters legally.
Examples
Born 15 March 1990, age on 26 September 2026: 36 years, 6 months and 11 days — 13,344 days in total. The next birthday (37th) is on 15 March 2027, 170 days away.
A youth competition requires entrants to be under 16 on 1 January 2027. Someone born on 20 December 2010 is 16 years and 12 days old on that date, so they would not qualify — even though they were 15 when the entry period opened.
Tips
- For a gap between any two dates — not just birthdays — use the Date Difference Calculator, which can also count weekdays and include the end date.
- Need an age as a percentage of something, such as the share of a working life completed? Combine the total days here with the Percentage Calculator.
- Time zones can matter for someone born near midnight. This tool works with calendar dates only, which is what almost every official form uses.
- Nothing you enter is stored or sent anywhere — the calculation happens in your browser.
Frequently asked questions
How do I calculate my exact age?
Count the complete years since your date of birth, then the complete months since your last birthday, then the remaining days. This calculator does all three steps for you and accounts for months of different lengths and leap years.
How are leap years handled?
Every leap day is included in the total day count. Someone born on 29 February reaches their birthday on 28 February in non-leap years in this calculator.
Can I calculate age on a future date?
Yes. Change the "Age on this date" field to any date after the date of birth, such as a deadline or an event.
Why is "total months" not equal to years × 12 plus months?
It is — total months is the number of complete calendar months. The remaining days are not counted as a partial month.
Last updated . Spotted a mistake? Let us know and we will correct it.