Quick Answer: To calculate your exact age, subtract your birth date from today's date in three parts: years, then months, then days, borrowing a month or a year when needed. For example, someone born on 15 August 1995 is 31 years, 1 month and 9 days old on 24 September 2026. Use the free EasifyMe Age Calculator to get your exact age, down to the second, instantly.
Key Takeaways
- Exact age is measured in completed years, months and days.
- When the day or month in today's date is smaller than in the birth date, you borrow from the next unit.
- Months have different lengths, so "1 month" is not always 30 days.
- Leap-year birthdays (29 February) need special handling in non-leap years.
- For spreadsheets, Excel and Google Sheets can calculate age with the DATEDIF function.
How Age Is Calculated
Your age in years is the number of full years since you were born. Your birthday this year only counts once it has arrived. Most forms need just this number, but schools, sports leagues, visa applications and medical records often ask for age in years, months and days.
The method works like the subtraction you learnt at school, but with calendar units instead of tens and hundreds:
Write today's date and the birth date as day, month and year.
Subtract the days. If today's day is smaller than the birth day, borrow the number of days in the previous month and reduce the months by one.
Subtract the months. If today's month is smaller, borrow 12 months and reduce the years by one.
Subtract the years.
Worked Examples
Example 1: No borrowing needed
Born: 15 August 1995. Today: 24 September 2026.
|
Unit |
Calculation |
Result |
|
Days |
24 − 15 |
9 days |
|
Months |
9 − 8 |
1 month |
|
Years |
2026 − 1995 |
31 years |
Age: 31 years, 1 month and 9 days. That is 11,363 days, or about 1,623 weeks. The next birthday, on 15 August 2027, is 325 days away.
Example 2: Borrowing a month and a year
Born: 28 November 2000. Today: 10 March 2026.
Days: 10 is smaller than 28, so borrow the 28 days of February 2026. 10 + 28 − 28 = 10 days, and March becomes month 2.
Months: 2 is smaller than 11, so borrow 12 months. 2 + 12 − 11 = 3 months, and 2026 becomes 2025.
Years: 2025 − 2000 = 25 years.
Age: 25 years, 3 months and 10 days. A simpler check: from 28 November 2025 to 28 February 2026 is 3 months, and from 28 February to 10 March is 10 more days.
Try it free: Skip the manual borrowing. The free Age Calculator shows your age in years, months, days, hours, minutes and live-ticking seconds, plus a birthday countdown and milestone timeline.
Example 3: Birthdays at the end of a month
Born: 31 January 1990. On 24 September 2026, the age is 36 years, 7 months and 24 days.
Month-end birthdays are where calculators can differ by a day, because some months have no 31st. A reliable calculator steps forward month by month from the birth date, which is what the Age Calculator does, rather than assuming every month has 30 days.
What About 29 February Birthdays?
People born on 29 February only see their exact birthday in leap years. In other years, most people celebrate on 28 February or 1 March. For legal purposes, such as when someone turns 18, the rule depends on the country, so check local law if an exact date matters.
A leap year occurs every 4 years, except for years divisible by 100 but not by 400. So 2000 was a leap year, but 1900 was not. The next leap day is 29 February 2028.
How to Calculate Age in Excel or Google Sheets
If a birth date is in cell A2, these formulas return age from today's date:
Years: =DATEDIF(A2, TODAY(), "Y")
Remaining months: =DATEDIF(A2, TODAY(), "YM")
Remaining days: =DATEDIF(A2, TODAY(), "MD")
Total days: =TODAY() - A2
Microsoft notes that the "MD" option can give inaccurate results in some cases, so double-check the days figure for month-end birthdays, or use the Age Calculator for one-off checks.
Other Ways People Count Age
- Age in days or weeks is common for babies and in medical settings.
- East Asian age reckoning traditionally counted a newborn as one year old. South Korea officially standardised on international age for legal and administrative purposes in June 2023.
- Age on a specific date, rather than today, is needed for exam eligibility, school admission and job applications with age cut-offs. To count the time between any two dates, use the Date Calculator.
Beyond Human Age
Curious how old your dog is in human years? The simple "multiply by 7" rule is a myth, and the real answer depends on size and breed. Try the Dog Age Calculator for a better estimate.
Age also appears in many health measures. The BMI Calculator uses your details to estimate your healthy weight range, and our guide on how to calculate BMI explains what the number means. To work out what percentage of a year has passed since your last birthday, use the Percentage Calculator. Browse more everyday tools in our calculators collection.
Common Mistakes to Avoid
- Subtracting only the years. 2026 − 1995 = 31 only if the birthday has already passed this year.
- Assuming every month has 30 days. This causes off-by-one-day errors.
- Using the wrong reference date. Exam and job forms often ask for age on a cut-off date, not today.
- Mixing date formats. 03/04/2026 is 3 April in India and the UK, but 4 March in the US.
Frequently Asked Questions
How do I calculate my exact age?
Subtract your birth date from today's date in days, months and years, borrowing a month or year when needed. An age calculator does this automatically and handles different month lengths and leap years.
How old am I if I was born in 2000?
In 2026, you are 26 if your birthday has already passed this year, or 25 if it has not. Enter your full date of birth in an age calculator for the exact figure.
How do I calculate age in days?
Subtract your birth date from today's date. In Excel or Google Sheets, =TODAY() − A2 gives the total days when A2 holds your birth date.
How is age calculated for a 29 February birthday?
In non-leap years, people usually celebrate on 28 February or 1 March. Legal age rules vary by country. Your age in completed years increases every year either way.
Is the EasifyMe Age Calculator free?
Yes. It is free, needs no signup, and works in your browser. It also shows a birthday countdown, zodiac sign and life milestones.
How do I calculate my age on a specific date?
Use the same method, but replace today's date with the date you need, such as an exam or job application cut-off. The Date Calculator can also count the exact time between any two dates.
