How to Calculate Age
Enter your date of birth into the calculator above. Use the optional "Target Date" field to calculate your age as of any specific date rather than today. Results include your exact age plus totals for months, weeks, days, and hours lived.
Age Calculation Formula
Age is determined by comparing your birthdate to the target date, fully accounting for leap years and varying month lengths:
Years = floor((targetDate − birthDate) / 365.25)
Months = (targetYear − birthYear) × 12 + (targetMonth − birthMonth)
Days = totalMilliseconds ÷ 86,400,000
Weeks = floor(Days ÷ 7)
Example Calculation
Date of birth: March 15, 1990 → Target: February 22, 2025
Age → 34 years, 11 months, 7 days
Months → 419 total months
Weeks → 1,822 total weeks
Days → 12,762 total days
Next B-Day → March 15, 2025 (21 days away)
Frequently Asked Questions
How accurate is this age calculator? +
Highly accurate. It accounts for leap years and varying month lengths using precise JavaScript Date arithmetic, computing differences down to the exact day.
Can I calculate age for a future date? +
Yes! Set any future date in the "Target Date" field to see how old you'll be on a specific anniversary, event, or milestone. The date of birth must remain in the past.
Does it account for leap years? +
Absolutely. Leap years are fully factored into all outputs — years, months, days, weeks, and hours. February 29 birthdays are handled correctly.