How to Calculate Your Age
Calculating your exact age involves more than simply subtracting your birth year from the current year. To get an accurate age in years, months, and days, you need to account for whether your birthday has occurred this year and the varying lengths of months.
Step-by-Step Age Calculation
Start with the years
Subtract your birth year from the current year to get a preliminary age in years.
Check the months
If your birthday month hasn't occurred yet this year, subtract 1 from the years.
Calculate remaining months
Count the months from your last birthday to the current month.
Count the days
Calculate the remaining days in the current month since your birth day.
Example Calculation
If you were born on March 15, 1990, and today is December 31, 2025:
- Years: 2025 - 1990 = 35 years
- Months: December - March = 9 months
- Days: 31 - 15 = 16 days
- Result: 35 years, 9 months, 16 days
Tip: Our calculator handles all the complex math automatically, including leap years and months with different numbers of days. Simply enter your birth date and get instant, accurate results.
Age Milestones & Life Stages
Understanding age milestones helps contextualize your journey through life. Here are significant age-related milestones recognized in various contexts.
Legal Milestones (US)
- 16: Driving permit in most states
- 18: Legal adulthood, voting rights
- 21: Legal drinking age
- 25: Car rental without surcharge
- 35: Eligible for US President
- 62: Early Social Security benefits
- 65: Medicare eligibility
- 67: Full retirement age (born after 1960)
Life Stage Definitions
- 0-1: Infant
- 1-3: Toddler
- 3-12: Child
- 13-19: Teenager
- 20-39: Young Adult
- 40-59: Middle Age
- 60-79: Senior
- 80+: Elderly
Interesting Age Facts
Interesting Age Statistics
Here are some fascinating statistics about age and time that help put your life into perspective.
| Age | Days Lived | Weeks Lived | Hours Lived |
|---|---|---|---|
| 1 year | 365 | 52 | 8,760 |
| 10 years | 3,652 | 521 | 87,648 |
| 25 years | 9,131 | 1,304 | 219,144 |
| 50 years | 18,262 | 2,609 | 438,288 |
| 75 years | 27,393 | 3,913 | 657,432 |
| 100 years | 36,525 | 5,218 | 876,600 |
Time Perspective
- The average person spends about 26 years sleeping in their lifetime
- You will breathe approximately 672,768,000 times by age 80
- Your heart will beat about 3 billion times in an average lifespan
- The average person walks about 100,000 miles in their lifetime
- You will spend about 5 years of your life eating
Fun Fact: If you live to be 80 years old, you will have experienced approximately 29,200 days, 4,171 weeks, or about 2.5 billion seconds!
How We Calculate Age
Our age calculator uses precise date arithmetic to calculate your exact age. Here's the methodology we use to ensure accuracy.
Calculation Methodology
1. Years Calculation
We subtract the birth year from the current year, then adjust if the birthday hasn't occurred yet.
years = currentYear - birthYear - (birthday hasn't occurred ? 1 : 0)2. Months Calculation
We calculate the months difference, adjusting for cases where the day hasn't been reached.
months = currentMonth - birthMonth (adjusted for negative values)3. Days Calculation
We calculate remaining days, borrowing from the previous month if needed.
days = currentDay - birthDay (adjusted for negative values using previous month's length)4. Total Days Calculation
We calculate the absolute difference in milliseconds and convert to days.
totalDays = Math.floor((currentDate - birthDate) / (1000 x 60 x 60 x 24))Leap Year Handling
Our calculator properly accounts for leap years:
- Leap years occur every 4 years (divisible by 4)
- Exception: Years divisible by 100 are not leap years
- Exception to exception: Years divisible by 400 are leap years
- February has 29 days in leap years, 28 days otherwise
Accuracy Note: Our calculations are based on the Gregorian calendar, the most widely used civil calendar worldwide. Results are accurate to the day level.