Age Calculator

What is age calculator?

An age calculator tells you exactly how old you are — or how old someone else is — in years, weeks, days, and even hours. Unlike a basic subtraction of birth year from the current year, this tool accounts for the specific day of the year and handles leap years through a 365.25-day average. Enter the birthday as a day-of-year (1–365), the current date as a day-of-year, and the number of years ago the person was born, and the calculator does the rest. This is useful for filling out forms that require exact age, calculating age for school enrollment cutoffs, checking age eligibility for services, or just satisfying curiosity. It also computes total hours lived — a fun number for birthday cards and milestones. All calculations are private and run in your browser.

How to use this calculator

1. Enter your birthday day of year (1-365).
2. Enter your today day of year (1-365).
3. Enter your birth year offset (years ago).
4. Click the "Calculate" button.
5. View your result instantly — the main result is displayed prominently at the top with a detailed breakdown below it.

When to use this calculator

• Finding your exact age in years, months, weeks, days, and hours for forms
• Calculating age eligibility for school, sports, or government programs
• Determining the age difference between two people
• Generating fun stats (total days or hours alive) for birthday celebrations
• Checking if someone meets a minimum age requirement for a service or product