Age Calculator: Years, Months & Days

Age Calculator: Years, Months, Days & Full Time Breakdown

Calculate age from date of birth. Exact chronological age in years, months, days plus total weeks, hours, minutes, seconds. Leap years and leap-day birthdays handled. Next birthday countdown. Western age. Free, runs locally, no sign-up.

What This Age Calculator Does

This age calculator computes your exact chronological age from any two dates. Enter your date of birth and an "as of" date (defaults to today) to get your age in years, months, and days, plus totals in weeks, days, hours, minutes, and seconds. It also shows a countdown to your next birthday. Leap years, variable month lengths, and leap-day birthdays (February 29) are handled automatically.

Who it helps:

Anyone who needs an exact age: parents tracking milestones, travelers verifying passport validity, HR teams confirming employment eligibility, or anyone curious about their precise age in multiple time units.
What it does not do:

It does not calculate Korean age, lunar-calendar age, or insurance-specific "age nearest birthday" conventions. It uses the Western chronological standard: 0 at birth, incrementing on each birthday.

How to Calculate Age from Date of Birth

The age formula

Exact chronological age is computed from the total days between your birth date and the "as of" date, then converted into years, remaining months, and days. Month lengths (28–31 days) and leap years are applied automatically. The algorithm works as follows: start from the birth date, count complete years (checking whether the birthday has passed in the current year), then count remaining complete months, then remaining days.

Leap year rule:

A year is a leap year if divisible by 4, except century years not divisible by 400. This means 2000 was a leap year, but 1900 was not. Each February 29 in the span between your dates is counted.
Leap-day birthdays:

If you were born on February 29, your birthday in non-leap years is treated as February 28 for age-counting purposes, the standard legal convention in most jurisdictions.

Worked example

Birth date: March 15, 1990. As-of date: January 10, 2026.

Complete years: March 15, 1990 → March 15, 2025 = 35 years (birthday has not yet occurred in 2026).
Remaining months: March 15 → January 10 goes backward, so we count from the last birthday: March 15, 2025 → January 10, 2026 = 9 months and 26 days.
Result: 35 years, 9 months, 26 days.
Total days: approximately 13,050 (the calculator counts every day including leap days).

Time units:

Total days are converted to weeks (÷ 7), hours (× 24), minutes (× 60), and seconds (× 60) for the full breakdown display.
Edge case, same-day birth:

If the as-of date equals the birth date, age is exactly 0 years, 0 months, 0 days.

Western vs. Korean and Other Age Systems

This calculator uses Western chronological age: 0 at birth, 1 on your first birthday. Korean age and some East Asian systems count from conception or increment on Lunar New Year, so the same dates can yield different ages. The Information Hub above summarizes how we apply the Western standard.

How to Use the Age Calculator

Date of Birth:

Enter your birth date. Use the date picker for easy month/year navigation.
Age at the Date of:

Defaults to today. Change it to find your age at a specific date, a milestone birthday, retirement, or any point in time.
Exact Chronological Age:

Main result shows years, months, and days in bold. Below: total months, weeks, days, hours, minutes, seconds, all locale-formatted.
Next Birthday:

Time until your next birthday (e.g., "5 Months, 12 Days"). Leap-day birthdays use Feb 28 in non-leap years.
Two people:

Need the gap between two birth dates instead of one person's age? Use the Age Difference Calculator for years, months, days, and milestones.

Age Milestones and Legal Ages by Country

Many life events and legal rights are tied to specific ages. Knowing your exact age, down to the day, matters when eligibility hinges on a birthday. This calculator can verify whether you have reached a milestone by setting the "as of" date to the relevant deadline.

United States:

Driving permit: 15–16 (varies by state). Voting and military service: 18. Alcohol purchase: 21. Full Social Security retirement: 66–67 (birth-year dependent). Medicare eligibility: 65.
United Kingdom:

Driving (car): 17. Voting: 18. Alcohol purchase: 18. State pension: 66 (rising to 67 by 2028).
Canada:

Driving: 16 (varies by province). Voting: 18. Alcohol: 18 or 19 depending on province. Canada Pension Plan: early at 60, standard at 65.
European Union (general):

Driving (car): 17–18. Voting: 18 (16 in Austria and Malta). Alcohol: 16–18 depending on country and drink type. Retirement: 62–67 depending on country.
Japan:

Age of majority was lowered from 20 to 18 in 2022. Drinking and smoking remain 20. Driving: 18. National pension: 65.
Australia:

Driving (learner permit): 16. Voting: 18 (compulsory). Alcohol: 18. Age Pension: 67.

Age Calculator FAQ

How do I calculate my age from my date of birth?

Age is the years, months, and days between your birth date and the "as of" date. The calculator uses total days between the two dates, then applies month lengths and leap years to get an exact breakdown (including total weeks, hours, minutes, seconds). See the Information Hub in the calculator for the exact formula and rules.

Why does the second date default to today?

"Age at the Date of" defaults to today so you see your current age right away. Change it to any date to find your age at that moment, milestone birthdays, retirement, or historical events.

How do leap years affect my age in days?

Leap years add Feb 29 every four years (except most century years). Each Feb 29 in your span is counted. Example: born Feb 28, measured Mar 1 in a leap year = 2 days; in a non‑leap year = 1 day.

I was born on February 29. How is my age calculated?

Standard legal practice: leap-day birthdays count as Feb 28 in non-leap years. In 2025 (non-leap), your birthday is Feb 28 for age purposes. The Next Birthday countdown uses the same rule.

What is Western age vs Korean age?

Western chronological age counts from birth: 0 on your birth day, 1 on your first birthday. Korean age (and some East Asian systems) often counts from conception or bumps everyone on Lunar New Year, so a baby can be "1" at birth. This calculator uses the Western standard.

Can I find my age at a future or past date?

Yes. Set "Age at the Date of" to any date for your exact age at that moment. Handy for retirement planning, "How old will I be in 2030?", or contractual age checks.

Age Calculator: Years, Months, Days & Full Time Breakdown

Dates

Totals

How this works

Date used for this calculation

Month lengths and day subtraction

Total days and derived units

Western age vs. other conventions

Leap years and Feb 29

Understanding Your Age

What You Get

Exact breakdown

Next birthday

Any date