Calculate your exact age in years, months, and days from your date of birth. See your next birthday countdown and age milestones.
Age Calculator
Years
Months
Days
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How to Calculate Your Exact Age
Your age in everyday conversation is simply the number of full years since your birthday. But your exact age includes the remaining months and days — which matters for legal purposes, medical screening timelines, and pension calculations.
Why Age Calculations Are Trickier Than They Seem
Months have different lengths (28–31 days), and leap years add an extra day every four years. This means you cannot simply divide total days by 365.25 and get a correct years-months-days breakdown. A proper age calculator accounts for each calendar month's actual length.
Age in Different Cultures
Western: Age counts from birth (0 at birth, becomes 1 on first birthday)
Korean (traditional): Age starts at 1 at birth, adds 1 every Lunar New Year — so a baby born in December is 2 by February
East Asian lunar: Similar counting, varies by country and context
Legal age: In most countries, legal milestones (voting, driving) are based on your Gregorian birthday
Common Age Milestones
Age
Common Milestone
18
Legal adult in most countries; voting age
21
Legal drinking age in USA; full legal capacity in some countries
25
Car rental discounts; lower auto insurance rates
65 / 67
Standard retirement and pension eligibility age
Frequently Asked Questions
Subtract your date of birth from today's date — the difference in milliseconds divided by 86,400,000 gives your age in total days. Our calculator shows this automatically. For example, a person born on January 1, 2000 is 9,067+ days old as of late 2024.
Completed years (also called 'age last birthday') is how old you are right now. Running year means you're in your Xth year — so a 25-year-old is in their 26th year. Legal and medical documents almost always use completed years.
If you were born on February 29, your non-leap-year birthdays are treated as March 1 in most legal jurisdictions (some use February 28). Our calculator uses the calendar day difference, so it correctly handles leap years in the total days count.
Yes — change the 'Age As Of Date' field to any past or future date. This is useful for calculating how old someone was at a historical event, or how old you will be at a future milestone.