Age Calculator: Calculate Exact Age in Years, Months, and Days

Calculating age seems simple, but exact age in years, months, and days requires accounting for varying month lengths and leap years.

How Age Calculation Works

Age is the difference between the current date and birthdate. Years are counted first, then remaining months, then remaining days. This gives the most intuitive result.

Leap Years and February 29

Leap years occur every 4 years (with exceptions for century years not divisible by 400). People born on February 29 typically celebrate on February 28 or March 1 in non-leap years.

Why Age Matters

Legal purposes: Eligibility for voting, driving, drinking, retirement
Medical purposes: Dosage calculations, developmental milestones
Financial purposes: Retirement planning, insurance rates
Fun purposes: "You're X days old!" facts

Birthday Countdown

Calculate days until your next birthday by finding the difference between today and your next birthday date. Account for whether your birthday has passed this year.

Frequently Asked Questions

How do I calculate age in months?

Multiply years by 12, then add remaining months. For exact months including days: count full months from birth month to current month, adjusting for day of month.

When is a leap year?

A year is a leap year if divisible by 4, except century years must be divisible by 400. So 2000 was a leap year, but 1900 was not.

What is my exact age if born on February 29?

In non-leap years, most people celebrate on February 28 or March 1. Legally, it varies by jurisdiction—some recognize March 1.