What this tool does
Calculates the precise difference between two dates in years, months, and days. Handles leap years and month-length variations automatically.
Converter and calculator
Age Calculator
Find out exactly how old you are in years, months, and days — or calculate the age of anything with a known start date. Works for birthdays, anniversaries, asset ages, and contract durations.
Complete guide
How to use Age Calculator
Unit converters guide for age calculator users.
The age calculator takes two dates — a start date (like a birthday) and an end date (usually today) — and returns the exact difference broken down into years, months, and days. Unlike simple subtraction, it accounts for leap years and varying month lengths so the result is always precise.
Common uses include calculating someone's exact age for official documents, verifying age eligibility (voting, driving, alcohol), calculating how long you've been at a job, or finding the age of a business or asset for accounting purposes.
All calculation runs in your browser using JavaScript's Date API — no data is sent anywhere.
How to use it
Enter the start date (e.g. your birthday) and the end date (today is pre-filled). Click Calculate. The result shows years, months, days, and total days.
Best practices
For official documents, double-check against a government-issued ID. For age eligibility checks, use the exact time if the cutoff is today.
Quick checklist
- Enter the birth or start date in the first field.
- The end date defaults to today — change it if you need a future or past age.
- Read the result in years + months + days for precision.
- Total days shown is useful for contract or warranty calculations.
Answers
Age Calculator FAQs
Does the calculator account for leap years?
Yes. It uses JavaScript's native Date object which correctly handles all leap year rules including century exceptions.
Can I calculate a future age?
Yes — set the end date to any future date to see what age someone will be then.
Is time-of-day factored in?
No. The calculator works in whole days. For hour-precision, use the Date Difference calculator.
Can I calculate the age of a company or asset?
Yes — enter the founding/purchase date as the start and today as the end.