Calculate exact age in years, months and days from a date of birth, plus total days, weeks and months lived and the countdown to the next birthday.
How age is calculated
Your age in completed years increases on each birthday. To get the exact age, the calculator counts full years, then full months, then the remaining days between your date of birth and the target date, borrowing days from the previous month when needed, the same way people count age by hand.
Worked example
Someone born on June 15, 1990 is 36 years, 3 months and 29 days old on October 14, 2026, having lived 13,270 days. Their next birthday is June 15, 2027.
Uses for an exact age
- Checking eligibility for age-based programs, such as retirement accounts, Medicare or Social Security.
- Calculating a child's age in months for development milestones.
- Filling in forms that need age on a specific date.
What about leap-day birthdays?
People born on February 29 officially turn a year older on February 28 or March 1 in non-leap years, depending on the law or organization. The calculator counts the birthday on March 1 in those years.
Frequently asked questions
Can I calculate age on a future date?
Yes. Change the "age on this date" field to any date after the birth date.
Why do total months not equal years × 12?
Total months adds the extra months beyond the last birthday, so 36 years and 3 months is 435 months.
Related tools
Results are estimates for planning and education only. They are not financial, tax, legal or medical advice. Check important numbers with a qualified professional.