Age Calculator

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

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Enter your values and click Calculate

Find your exact age down to the day with this precise age calculator. Enter your birth year, month, and day and the tool instantly tells you how old you are in years, months, days, total weeks lived, and total days lived — all calculated from today's date. This is useful far beyond simple curiosity: insurance applications ask for your age in years and months, pediatric growth charts reference age in months for children under two, and retirement planners need an exact age to determine Social Security eligibility windows. Medical professionals use age in months to assess developmental milestones for young children, while actuaries and legal documents often require age broken down to the month. Genealogists use exact day-counts to verify historical records and confirm ages listed on census documents. People celebrating milestone birthdays enjoy seeing the precise number of days they have been alive — 10,000 days is a widely celebrated personal milestone that falls somewhere in the late 20s for most people. Athletes and fitness enthusiasts track age in weeks to follow training cycles tied to biological development. The calculator correctly handles leap years, so someone born on February 29 receives an accurate count without errors. Whether you are completing a form, settling a friendly debate, or planning a milestone celebration, this tool delivers the complete breakdown instantly.

How It Works

The calculation starts by subtracting the birth year from the current year to get a preliminary year count. Then it compares birth month and day to today's month and day. If today's day is earlier in the year than the birthday, one year is subtracted and twelve months are added to the month difference; if the day-of-month component is negative, the prior month's length is borrowed. This three-step year-month-day decomposition correctly handles all calendar edge cases, including February birthdays in leap years. For total days, the calculator takes the raw millisecond difference between the birth timestamp and today's date, then divides by 86,400,000. Total weeks divides total days by 7. Total months is computed as (years × 12) plus the remaining months, providing a single cumulative figure useful for medical and developmental tracking. JavaScript's built-in Date object handles leap years natively, so no manual correction for February 29 is needed.

Examples

Born January 15, 1990
Calculating the exact current age for someone born in 1990.
Result: 35 years old as of March 2026, with a full breakdown in months, weeks, and total days lived.
Born July 4, 2000
A person born on Independence Day 2000.
Result: 25 years old (as of July 4, 2025), with over 9,000 total days lived.
Born February 29, 2000
A leap-year birthday, testing correct date handling.
Result: 26 years old in 2026, with the leap-day birthday correctly counted without errors.

Frequently Asked Questions

How are leap years handled?
The calculator uses JavaScript's built-in Date object, which correctly manages leap years. A person born on February 29 will have their birthday recognized in leap years and the total-day count will always be accurate regardless of how many leap years fall between their birth date and today. The raw millisecond difference used for the total-days calculation inherently accounts for every leap day in the range without any special-case logic.
Can I calculate the age between two historical dates?
This calculator always measures from the entered birth date to today's date. If you need the elapsed time between two specific historical dates — for example, how old someone was when they died, or how long ago a historical event occurred — a date-difference calculator lets you specify both the start and end date independently. That approach gives you full control over both endpoints rather than anchoring to today.
Why does my total weeks count seem slightly off?
Total weeks is calculated as the floor of total days divided by 7. Since weeks do not align perfectly with calendar months and years, the weekly count may appear slightly inconsistent with the year-month-day breakdown — but both figures are mathematically correct from their own perspective. The year-month-day output uses calendar arithmetic; the total-days and total-weeks outputs use exact elapsed time. They measure the same span two different ways.

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