Age Calculator
Enter a birth date below to instantly get age in years, months, and days.
How Age Is Calculated
Subtract year, month, and day separately, borrowing a month (adding that month's day count) whenever the day subtraction goes negative, and borrowing a year (adding 12 months) whenever the month subtraction goes negative.
Worked example
Born June 15, 1990. As of September 6, 2026.
Years: 2026 − 1990 = 36. Months: 9 − 6 = 3. Days: 6 − 15 = −9.
Days is negative, so borrow a month: months = 2, and add August's 31 days: −9 + 31 = 22.
Age: 36 years, 2 months, 22 days (13,232 total days)
Frequently Asked Questions
How do you calculate age in years, months, and days?
Subtract the birth year, month, and day from the reference date's year, month, and day. When the day subtraction goes negative, borrow a month and add that month's day count; when the month subtraction goes negative, borrow a year and add 12 months.
What happens with a Jan 31 birthday when the next month is shorter?
February has no 31st, so a full month isn't considered complete until the date actually reaches the birth day. Checking a Jan 31 birth date against March 1 reports 0 months and 29 days rather than a fraction of a month.
How is a Feb 29 (leap day) birthday handled in a non-leap year?
Since Feb 29 doesn't exist in a non-leap year, this calculator treats March 1 of that year as the completed birthday — so someone born Feb 29, 2020 turns exactly 1 year old on March 1, 2021.
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