Find your exact age in years, months, days, and hours — instantly.
Leave blank to use today
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Years
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Months
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Days
Total days alive
Total hours alive
Next birthday in
What is an Age Calculator?
An age calculator is a tool that determines a person's exact age by measuring the time elapsed between their date of birth and a given reference date. Unlike simply subtracting years, a precise age calculator accounts for varying month lengths, leap years, and whether a birthday has occurred yet in the current year.
CalcsYard's age calculator goes beyond just years — it shows your age broken down into years, months, and days, your total days and hours alive, and the number of days until your next birthday. It works for any date from the past to the future.
How to Use the Age Calculator
1Enter your Date of Birth using the date picker.
2Optionally, set an Age as of date to calculate age on a specific day instead of today.
3Click Calculate Age.
4View your age in years, months, days, plus total days alive and next birthday countdown.
Formula
Age = Target Date − Date of Birth
Years = Full calendar years elapsed
Months = Remaining full months after whole years
Days = Remaining days after whole months
Total Days = (Target Date − DOB) in milliseconds ÷ 86,400,000
Next Birthday:
Set birthday month/day in current year
If already passed → advance to next year
Days until = Birthday Date − Today
Frequently Asked Questions
Age is calculated by finding the difference between the birth date and the target date (today or a custom date), accounting for leap years and varying month lengths. Whole years are counted first, then remaining whole months, then remaining days.
Yes. Use the "Age as of" field to set any target date — past or future — and the calculator will show the exact age on that date. This is useful for legal purposes, insurance forms, or simply curiosity.
Yes. The calculator uses JavaScript's native Date object which correctly handles leap years (years divisible by 4, except century years not divisible by 400). Your total days alive figure will accurately include any leap years in your lifespan.
The calculator shows your total age in days in the result section. It counts every calendar day from your birth date to today (or the selected target date). A person who is 30 years old is approximately 10,957 days old.
Leap day birthdays (February 29) are fully supported. In non-leap years, the next birthday is counted as March 1. The calculator handles this edge case correctly.