Age Calculator
Calculate exact age in years, months and days, plus total months, weeks, days and the time until the next birthday.
Enter a date of birth and the date you want to calculate age on.
Exact age
Age breakdown
About the Age Calculator
When an exact age matters, subtracting the year numbers is not enough. This calculator works through the calendar difference between a birth date and a chosen date so the result can be shown in complete years, months and days.
Calendar age is affected by different month lengths and leap years. That is why an exact age calculation needs date arithmetic rather than a single fixed number of days per year.
How to Use the Age Calculator
- Enter the date of birth or starting date exactly as it appears on the relevant record.
- Choose the date on which you want the age calculated. Use today only when the question genuinely asks for current age.
- Calculate the result and review the years, months and days separately.
- For eligibility or legal cutoffs, compare the calculated age with the rule used by the organization because some rules count dates differently.
How the Calculation Works
The calculator first compares the year, month and day components of the two dates. It subtracts complete calendar years, then complete months and finally the remaining days while respecting the actual length of each month.
Leap years and month boundaries are handled by calendar dates rather than by assuming every year has 365 days or every month has 30 days. Additional totals, such as total days lived, are derived from the elapsed date interval.
Worked example
Age Calculator Worked Example
Born 10 May 2000, age on 31 August 2026
From 10 May 2000 to 10 May 2026 is 26 complete years. From 10 May to 10 August is 3 complete months, and from 10 August to 31 August is 21 days. The calendar age is therefore 26 years, 3 months and 21 days.
Result guide
Understanding Your Age Calculator Result
Use the years-months-days result for calendar age. Total days or weeks answer a different question and should not be converted back into age by dividing by an average year length when an exact calendar result is required.
Before you rely on the answer
Assumptions and Limitations
- The birth/start date and comparison date are valid Gregorian calendar dates.
- The comparison date is not earlier than the birth/start date unless the calculator explicitly supports reverse intervals.
- Legal or institutional age rules may define eligibility cutoffs differently from ordinary calendar age.
Practical tip
Using This Result in Practice
For forms and official records, calculate age on the exact date specified by the form rather than assuming today. This is especially important for school admissions, insurance and age-limited programs.
Related calculations
Useful Calculations to Continue With
If you need the exact number of elapsed days rather than calendar age, use the Days Between Dates Calculator.
If the question involves a deadline measured in working days, use the Business Days Calculator instead of ordinary age/date arithmetic.
Common questions
Age Calculator FAQ
Why can two people born in the same year have different ages?
Age depends on whether each person’s birthday has occurred by the comparison date, not just on the difference between the two year numbers.
How are leap-day birthdays handled?
The calendar calculation follows the actual dates in each year. Legal treatment of a 29 February birthday for age-based eligibility can vary by jurisdiction, so verify the applicable rule when it matters.
Is total days divided by 365 an exact age?
No. Leap years and different month lengths make that only an approximation. Exact calendar age should be calculated from calendar boundaries.