Age Calculator
Work out exact age in years, months and days, plus total days lived and the next birthday.
Defaults to today. Change it to see an age on any date.
Age
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Enter a date of birth and this calculator returns exact age in years, months and days, the total number of days lived, and the countdown to the next birthday. Change the second date to see an age on any day in the past or future, for example on a school cut-off date or a retirement date.
Everything is calculated in your browser, so dates of birth are never uploaded.
How age calculator works
The tool counts whole calendar months between the two dates, then counts the leftover days. Years are those months divided by twelve. When a month is shorter than the birth day, such as a birth on the 31st, the anniversary falls on the last day of that month.
Total days come from the gap between the two dates as calendar days, so leap days are included automatically.
The formula
Age = whole years + whole months + remaining days between the two dates
Days lived = (later date − earlier date) in calendar daysA birthday on 29 February is treated as 1 March in non-leap years. Some legal systems use 28 February instead.
Worked example: born 15 May 1990, checked on 10 March 2024
The 34th birthday has not happened yet, so the age is 33 years.
From 15 May 2023 to 15 February 2024 is 9 months.
From 15 February to 10 March 2024 is 24 days, because 2024 is a leap year.
Age: 33 years, 9 months, 24 days, or 12,353 days in total.
When to use this tool
- Checking eligibility for a school year, a sports category or a minimum-age rule on a specific date.
- Finding the age a person will be on a future date, such as at a wedding or retirement.
- Counting days lived for a milestone, such as 10,000 days.
- Filling in forms that ask for age in years and months.
Common mistakes to avoid
- Subtracting birth year from current year. That is wrong for anyone whose birthday has not yet happened this year.
- Forgetting that leap years add a day, which shifts total-day counts.
- Using the wrong date order. The tool uses the year-month-day picker to avoid day and month being swapped.
Frequently asked questions
- How do I calculate my exact age?
- Count the full years from your birth date to today, then the full months since your last birthday, then the days since your last monthly anniversary. The calculator does this for you.
- How many days old am I?
- The result panel shows total days lived, counted as calendar days between your birth date and the chosen date.
- How is age calculated for a 29 February birthday?
- This tool treats 1 March as the birthday in non-leap years. Some places use 28 February, so check the rule for legal documents.
- Can I calculate age on a past or future date?
- Yes. Change the “age at” date to any date, and the age, days and countdown all update.
Learn more
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Results are for information only and are not financial, legal or medical advice. The calculation logic is covered by automated tests, and examples on this page are worked out and re-checked before publishing. Spotted a mistake? Tell us.