Age Calculator & Age Difference Calculator

How Age Is Actually Calculated

Calculating age sounds simple — subtract the birth year from the current year. But an accurate age calculator has to go a step further, working out complete years, months, and days by comparing the exact birth date to today's date, not just the years. That is why two people born in the same year can still have a different number of days lived, depending on their exact birth date.

Why Leap Years Make Age Calculation Tricky

Every four years, February gets an extra day — February 29 — to keep our calendar aligned with the Earth's orbit around the sun. This means people born on February 29, sometimes called "leaplings," only have their exact birth date appear on the calendar once every four years. In other years, their birthday is commonly observed on either February 28 or March 1. A properly built age calculator accounts for leap years automatically, so the total days and years shown are always accurate — no manual adjustment needed.

Age Calculator vs. Age Difference Calculator — What's the Difference?

The main age calculator on this page tells you how old you are today, based on your date of birth. The age difference calculator below it answers a different question — how far apart in age two people are, based on both of their birthdates. This is useful for comparing your age with a sibling, partner, friend, or colleague, and instantly seeing who is older and by exactly how much.

When People Use an Age Difference Calculator

Age gap questions come up more often than people expect — checking eligibility rules that depend on age difference, settling a friendly debate about who is older, or simply out of curiosity between siblings or partners. Instead of manually counting years and months between two dates, this tool gives an instant, accurate breakdown in years, months, days, and total days apart.

Frequently Asked Questions