Age Calculator

Your Lifespan in Numbers

Knowing your age in years is standard, but breaking it down into exact months, days, weeks, and hours provides a unique and often surprising perspective on the passage of time. Use our calculator for accurate administrative document preparation or simply to explore your chronological milestones.

The Mathematics of Age

Calculating someone's exact age is notoriously tricky to do in your head or on paper because the Gregorian calendar is highly irregular. A simple subtraction of the current year from your birth year often results in an inaccurate age if your birthday hasn't happened yet this year.

• Irregular Months: Months vary between 28, 29, 30, and 31 days. When calculating the exact 'days' remainder of your age, the calculator must determine exactly how many days were in the specific month of your birth, and the current month.
• Leap Years: Every four years (with a few century exceptions), an extra day is added to February. A 40-year-old has lived through 10 leap days, meaning they have lived 10 days longer than a straight 365-day multiplication would suggest.

Age Systems Around the World

How old you are depends on where you are. There are two primary ways cultures track human age:

• The Western System (Age = 0 at birth): Used by most of the world and by this calculator. You are considered 0 years old when you are born, and you turn 1 year old exactly 365 (or 366) days later.
• The Traditional East Asian System (Age = 1 at birth): Historically used in China, Korea, and other parts of East Asia. A child is considered 1 year old on the day they are born (accounting for the time spent in the womb). Furthermore, everyone's age increases by one year collectively on the Lunar New Year (or Solar New Year), regardless of their actual birth date.