Age Calculator
Your precise age in years, months, and days — plus total days alive and the countdown to your next birthday.
Calculate your exact age
How exact age is calculated
Counting age sounds trivial until you try to program it. "Years, months, days" requires borrowing, the same way long subtraction does: if the day-of-month hasn't arrived yet, you borrow days from the previous month; if the birth month hasn't arrived, you borrow a year. Because months have different lengths and leap years add a day, two people born one day apart can briefly differ by what looks like a whole month. This calculator handles the borrowing precisely, using the actual lengths of the actual months involved.
Worked example
Born June 15, 1990, calculating on June 10, 2026: the birthday hasn't arrived yet, so the answer is 35 years, 11 months, 26 days — not 36. Total days lived is the straight difference between the dates: about 13,144 days, leap days included automatically. Five days later, the odometer rolls over to 36 years, 0 months, 0 days.
Where exact age actually matters
Beyond curiosity, precise age computations show up in real paperwork: eligibility cutoffs for school enrollment and sports leagues, retirement and Social Security milestones (where months matter to the benefit amount), insurance rating, immigration forms, and medical dosing for infants, where age is tracked in weeks and days. "Days alive" is also just satisfying to know — your 10,000th day lands a few months past your 27th birthday, and your 20,000th in your mid-fifties.
Leap years and edge cases
A leap year adds February 29 roughly every four years (century years only if divisible by 400 — 2000 was a leap year, 1900 wasn't). People born on February 29 typically celebrate on February 28 or March 1 in common years, but their legal age still advances normally: laws count years elapsed, not calendar matches. This calculator uses real calendar arithmetic, so leap days are counted exactly once each.
Frequently asked questions
How many days old am I?
Enter your date of birth and today's date — the calculator shows total days lived, counting leap days exactly. Rough mental math: years × 365.25.
Why does the months part of my age look odd around month ends?
Because months have different lengths, 'one month after January 31' is ambiguous. The calculator borrows days from the actual previous month, the standard convention, so results near month boundaries can shift by a day or two versus other methods.
Can I calculate age at a date in the past or future?
Yes — set the 'Age on date' field to any date after the birth date: a historical date, a deadline, or a future birthday.
How does the next-birthday countdown handle February 29?
If the next calendar year has no February 29, the countdown targets March 1, the most common legal convention. Leap-day birthdays still get an exact count in leap years.
Is my 'real' age different in other systems?
Some cultures historically counted everyone as one year old at birth and added years at New Year (notably the traditional Korean system, officially retired in 2023). This calculator uses international age — time actually elapsed since birth.