This age calculator gives you your exact age broken down into years, months and days, plus total months, weeks and days lived. Enter your birth date and optionally a reference date — if left empty, today's date is used. Everything runs in your browser, so your personal information never leaves your device.
Leave empty for today
Enter your values to see the result.
Birth: 2000-01-15, Reference: 2024-06-20 → 24 years, 5 months, 5 days
A precise breakdown showing each unit separately.
Birth: 1990-06-15, Reference: (today) → 34 years, 3 months, 11 days (approx)
When no reference date is given, today's date is used automatically.
Birth: 2020-02-29, Reference: 2024-02-28 → 3 years, 11 months, 30 days
Leap year birthdays are handled correctly.
Age seems simple — you subtract the birth year from the current year — but precise age calculation is more nuanced. A person born on December 31, 2000 is only 23 years old on January 1, 2024, not 24. The month and day matter, and the exact number of days between dates determines whether a birthday has occurred yet this year.
This calculator handles all these edge cases, giving you an exact breakdown that accounts for varying month lengths, leap years, and the calendar progression.
The algorithm works in three steps:
Step 1: Count full years. Subtract the birth year from the reference year. If the reference month and day haven't reached the birth month and day yet, subtract one year.
Step 2: Count remaining months. After accounting for full years, count the full months between the birth day and the reference day. If the reference day is before the birth day in the month, subtract one month and carry over to the day count.
Step 3: Count remaining days. The leftover days are simply the difference between the reference day and the birth day, adjusted for the month boundary if needed.
This approach produces the same result you would get by counting on a calendar, which is what most official forms and legal documents expect.
Useful when a form asks for age in months rather than years. This is common for infants and toddlers, where "18 months" is more precise than "1 year and 6 months."
Commonly used in pregnancy tracking, where gestational age is measured in weeks. Also useful for project planning and sprint calculations.
The raw number of days lived. Useful for calculations that need a single number, such as averaging daily rates over a lifetime or computing exact durations for legal purposes.
Official forms — Many government and insurance forms require exact age in years, months and days rather than just years.
Medical records — Pediatric care often tracks age in months or weeks for precise developmental milestones.
Retirement planning — Knowing your exact age helps calculate when you reach specific milestones like 65 years or 30 years of service.
Genealogy — When researching family history, calculating exact ages at death or at significant life events provides more accurate records.
Legal documents — Contracts, wills and trusts often specify ages precisely, and exact calculations prevent disputes.
Your birth date stays in your browser. No data is sent to any server, and no calculation depends on external services. The algorithm uses standard calendar arithmetic with proper leap year handling, producing results that match manual calendar counting.
The calculator counts full years, then full months remaining, then the leftover days. For example, if you were born on January 15, 2000 and today is June 20, 2024, you have completed 24 full years, then 5 full months (January 15 to June 15), then 5 more days (June 15 to June 20). This method matches how age is commonly understood and avoids the inaccuracies of simply dividing total days by 365.
Yes, the calculator accounts for leap years when computing days in each month. Someone born on February 29 in a leap year will see their age calculated correctly in non-leap years, with the day count adjusted to reflect the actual calendar progression.
When no reference date is provided, the calculator uses today's date automatically. This is the most common use case — finding your current age. You can specify a different reference date if you want to calculate age at a specific point in time, such as for a form requirement or historical research.
Different contexts require different representations of age. Forms may ask for age in years only, while medical or legal documents might need total months or total days. The total weeks field is sometimes used in pregnancy tracking. Having all these values available means you can copy whichever format you need without doing additional calculations.
No, all calculations happen entirely in your browser. Your birth date is never transmitted to any server, stored, or logged. The JavaScript code runs locally and produces the result instantly. You can safely use this calculator with any date without privacy concerns.
Use the ISO format YYYY-MM-DD, for example 1990-06-15 for June 15, 1990. The year must be four digits, the month two digits (01 to 12), and the day two digits (01 to 31 depending on the month). Invalid dates like February 30 or month 13 will be rejected with an error message.
Last updated on 2026-09-26 · Written by UtiliaTools