Age Calculator
Find your exact age in years, months, and days — plus total weeks and days lived, and a countdown to your next birthday.
How age is calculated
Your age in years, months, and days is the calendar difference between your birth date and the target date, "borrowing" days and months where needed — the same way you'd work out a duration on paper. The totals (months, weeks, days) count actual elapsed calendar time, so leap days are already included.
Born March 15, 1990, measured on July 22, 2026: that's 36 years, 4 months, 7 days — about 436 months or 13,278 days.
Born July 20, 1969 (the day of the Moon landing), age on January 1, 2000: 30 years, 5 months, 12 days — about 11,122 days old on the eve of Y2K.
Beyond birthdays
The same date math answers a lot of practical questions: eligibility ages (driving, voting, retirement accounts), how old someone will be at a future event, or a pet's age. Change the "age at" date to any past or future day to see the age on that date. To count the gap between two arbitrary dates rather than an age, use the date calculator; for durations in hours and minutes, the time calculator.
Common age-related eligibility milestones (U.S.)
| Milestone | Typical age |
|---|---|
| Learner's permit | 15–16 |
| Vote / sign contracts | 18 |
| Rent a car without a young-driver surcharge | 25 |
| Penalty-free 401(k)/IRA withdrawals | 59½ |
| Full Social Security retirement age | 66–67 |
Common age-calculation mistakes
- Assuming a birthday changes "years old" at the exact minute of birth. Legal and calendar age changes at the start of the calendar day, not the exact time you were born.
- Handling Feb 29 birthdays inconsistently. Someone born on a leap day has no exact anniversary in non-leap years — different jurisdictions use Feb 28 or March 1 as the legal equivalent.
- Confusing "months lived" with a decimal fraction of a year. 29 years and 6 months is not "29.6 years" — 6 months is 0.5 of a year, not 0.6. Convert months to years by dividing by 12, not by treating them as tenths.
Frequently asked questions
How do I calculate my exact age?
Calendar difference between birth date and today, in years, months, and days — plus totals in weeks and days.
How is age calculated across leap years?
Actual calendar days are counted, so leap days are included automatically.
Can I calculate age at a past or future date?
Yes — set the "age at" date to any day.
Does a Feb 29 birthday change when someone legally turns a year older?
Depends on jurisdiction — most treat it as Feb 28 or March 1 in non-leap years, since there's no universal rule.
How many total days old am I at roughly 30 years old?
About 10,957 days — 30 years averaging 365.25 days each once leap years are accounted for.
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Last reviewed: September 2026.