Why does the 'months' count sometimes feel off by a day?

Months have different lengths (28–31 days), so 'one month' is not a fixed number of days. The calculator borrows days from the previous month when the current day-of-month hasn't been reached yet — the same logic used in standard date arithmetic.

Can I calculate age as of a future date?

Yes. Change the 'Calculate Age As Of' field to any future date. This is useful for checking how old someone will be at a specific event, such as a retirement date or a child starting school.

How is the 'next birthday countdown' calculated?

The calculator finds the next occurrence of your birth month and day on or after the reference date. If today is already past your birthday this year, it looks at next year's date. The countdown is the number of calendar days remaining.

Does the calculator account for leap years?

Yes. JavaScript's built-in Date object handles leap years correctly. If you were born on February 29, the calculator uses February 28 as your birthday equivalent in non-leap years when computing the countdown.

Age Calculator

Calculate your exact age in years, months, and days from your date of birth.

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Date of Birth

Calculate Age As Of

Enter your date of birth to calculate your age

How to Use

1
Click the 'Date of Birth' field and select or type your birth date.
2
The 'Calculate Age As Of' field defaults to today — leave it or change it to any other date.
3
Your exact age in years, months, and days appears instantly.
4
Check the birthday countdown panel to see how many days until your next birthday.

Use Cases

Legal Age Verification

Confirm whether someone has reached the legal age for voting, driving, drinking, or signing contracts on a specific date.

Medical & Pediatric Records

Doctors and nurses quickly determine a patient's age in months and days — critical for dosage and developmental milestones.

HR Onboarding & Retirement

Calculate an employee's exact age on a hire date or confirm retirement eligibility to the day.

Birthday Planning

Find out exactly how many days until your birthday (or a friend's) to plan a surprise well in advance.

Frequently Asked Questions

Calculate your exact age in years, months, and days from any date of birth. You can also find out how many days until your next birthday, and calculate age as of any past or future reference date — useful for legal, medical, or HR scenarios.

The calculator counts completed years, then completed months within the remaining partial year, then the remaining days. For example, someone born on March 15 who is checked on July 3 has 3 months and 18 days beyond their last birthday — not a simple 365-day division.

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