How to use this calculator
- Enter your date of birth.
- Leave Age on set to today, or change it to any later date to find an age on that day.
- If you were born on February 29, choose whether your birthday falls on February 28 or March 1 in non-leap years.
The result shows your age in years, months and days, your next birthday with the day of the week it falls on and how many days away it is, and your age converted to total months, weeks, days and hours. The steps underneath show exactly how the count was made.
How age is calculated
Age isn’t just “days divided by 365”. Years have 365 or 366 days and months run from 28 to 31 days, so the calculator counts on the calendar, the way you would with a wall calendar:
- Whole years. Count the birthdays you’ve had. Born June 15, 1990, you turned 36 on June 15, 2026.
- Whole months. From that last birthday, count how many times the 15th of a month has come around: July 15, August 15, September 15 and October 15 make 4 months.
- Remaining days. From October 15 to November 6 is 22 days.
So on November 6, 2026, that person is 36 years, 4 months and 22 days old.
The totals come from a simple subtraction of calendar days:
For the same example that’s 13,293 days, which is exactly 1,899 weeks, or 436 months and 22 days, or 319,032 hours. Total weeks are the days divided by 7 with the remainder shown separately. Total hours are whole days times 24.
All dates are handled as whole calendar days, so your time zone, daylight saving time and the hour you were born never shift the answer.
Months that end early
When you were born on the 29th, 30th or 31st, some months don’t have your day. The calculator counts a month as complete on the last day of a shorter month. For example, from January 31 to February 28 is one full month, and from January 31 to March 1 is 1 month and 1 day. This matches how spreadsheets and most date software add months.
Leap-day birthdays
If you were born on February 29, your actual birthday only appears every four years (with the exception of century years not divisible by 400, such as 2100). In the years in between there are two common choices:
| “Age on” date | Feb 28 rule | Mar 1 rule |
|---|---|---|
| February 28, 2025 | 25 years, 0 months, 0 days | 24 years, 11 months, 30 days |
| March 1, 2025 | 25 years, 0 months, 1 day | 25 years, 0 months, 0 days |
| February 28, 2026 | 26 years, 0 months, 0 days | 25 years, 11 months, 30 days |
| February 29, 2028 | 28 years, 0 months, 0 days | 28 years, 0 months, 0 days |
Example: born February 29, 2000.
The calculator uses February 28 unless you switch the option, so your age goes up on the last day of February. Choose March 1 if that’s how you celebrate, or if an official rule you need to meet counts it that way. Laws and agencies don’t all agree, so for anything legal, such as a driving or drinking age, check the rule that applies where you live.
Fun milestones in days
People celebrate round numbers of days too. For someone born on June 15, 1990:
| Milestone | Date reached |
|---|---|
| 10,000 days old | Tuesday, October 31, 2017 |
| 1 billion seconds old (about 11,574 days) | Monday, February 21, 2022 |
| 15,000 days old | Thursday, July 10, 2031 |
| 20,000 days old | Saturday, March 18, 2045 |
To find your own, use the date calculator: pick your birth date as the start, choose Add or subtract, and add 10,000 days.
Where an exact age matters
- School enrollment. Many districts use a cutoff such as “5 years old by September 1”. Set the “Age on” date to the cutoff.
- Benefits and retirement. Eligibility for programs often depends on reaching an age on a specific date. Our retirement calculator can help you plan the savings side.
- Health. Growth charts for children use age in months, and for babies the age in weeks. Expecting? The due date calculator counts pregnancy weeks.
- Contracts and deadlines. Insurance, visas and age-limited programs often care about your age on one exact day, not today.
Assumptions and limitations
- Ages are counted in whole calendar days in the Gregorian calendar, which the US and most of the world use. Dates are accepted from the year 1000 on. For dates before a country adopted the Gregorian calendar (1752 in Britain and its colonies), the historical calendar date may differ.
- The time of birth isn’t used, so the result is accurate to the day, not the hour.
- “Total hours” is whole days × 24 and ignores daylight saving changes.
- The weekday of birth is calculated, not looked up, so it works for any supported date.
Frequently asked questions
How do I calculate my exact age?
Count the whole years since your last birthday, then the whole months since that birthday's day of the month, then the days left over. Someone born June 15, 1990 is 36 years, 4 months and 22 days old on November 6, 2026. The calculator does this counting on the calendar, so leap years and short months are handled for you.
How many days old am I?
Subtract your birth date from today's date in whole calendar days. A person born June 15, 1990 is 13,293 days old on November 6, 2026, which is exactly 1,899 weeks. Enter your own birth date above to get your total in days, weeks, months and hours.
When do people born on February 29 celebrate their birthday?
In leap years, on February 29. In other years there's no single rule, so most people pick February 28 or March 1. This calculator uses February 28 by default and lets you switch to March 1, which changes the day your age ticks over in non-leap years.
What day of the week was I born?
Enter your date of birth and the calculator shows the weekday in the result. For example, January 1, 2000 was a Saturday and July 20, 1969, the day of the first Moon landing, was a Sunday.
Can I calculate someone's age on a past or future date?
Yes. Change the "Age on" date to any date after the birth date. This is useful for checking an age on a specific deadline, such as a school enrollment cutoff, the start of a contract or a future retirement date.
Why does the total in hours look so large?
The hours figure is your age in whole calendar days multiplied by 24. A 36-year-old has lived more than 300,000 hours. It ignores the time of day you were born and daylight saving changes, so treat it as an approximation to the nearest day.
Updated November 2026. Results are estimates for educational purposes and depend on the inputs you provide.