Calculate exact age, compare against any date, and browse birth-year quick links.
Enter your date of birth to calculate your exact age.
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Age Calculator
An age calculator tells you exactly how old you are — not just in years, but in months, weeks, days, and hours. It handles leap years, month-length differences, and custom end dates so the answer is always mathematically precise. ClockUnit's free version runs entirely in your browser with no sign-up.
How it works
Tap or click the Date of Birth field and choose your birth date from the picker. The calculator starts running immediately.
The end date defaults to today. Hit 'Till Date' to snap it back to now, or choose any past or future date to calculate your age at that point.
Your age in years, months, and days appears instantly on the card. Scroll down for your total days, weeks, hours, and next birthday countdown.
Features
Built for speed, accuracy, and privacy.
Get your precise age broken down into years, months, and days — not just a rounded number.
See your life in months, weeks, days, and hours — a fresh perspective on how much time you've lived.
One tap snaps the end date back to today. Instantly recalculates — no extra steps.
Always know how many days until your next birthday. Arrive at parties on time.
Calculate your age at any point in time — past or future. Great for contracts and milestones.
Results update the moment you change either date. No clicking required — just type and see.
All calculations run in your browser. Your dates are never sent to a server.
Fully responsive — phone, tablet, or desktop. No app to download.
Handles Feb 29 birthdays and leap years correctly so your count is always exact.
Use cases
More useful than you'd expect.
Share your exact age in years, months, and days on social media for a milestone birthday post.
Many forms require your precise age. Calculate it instantly for passports, wills, and applications.
Doctors and healthcare providers often need your exact age to the month for proper dosing and records.
Confirm you're in the right age bracket for running races, swimming events, and sports leagues.
Calculate exactly how far you are from retirement age and plan your savings timeline accordingly.
Check whether your child meets the cutoff age for enrollment, examinations, or grade placement.
Methodology
Subtract the birth year from the end year. If the birth month/day hasn't occurred yet in the end year, subtract one more year.
Subtract the birth month from the end month. If the birth day hasn't passed yet in the end month, subtract one more month and borrow days from the previous month.
Subtract the birth day from the end day. If the result is negative, borrow the total days of the previous month and add them.
The raw difference between the two dates in milliseconds, divided by 86,400,000 (ms per day). Leap years are included automatically.
Total days × 24. Exact to the day — partial hours (minutes and seconds) are not counted to keep the number clean.
FAQ
We count the full years from your birth date to the end date, then the remaining months, then the remaining days. If the end day is earlier than your birth day in the month, we borrow days from the previous month to ensure accuracy.
It resets the end date to today and immediately recalculates your age. It's highlighted in the accent color when the end date already equals today.
Yes. Change the 'Age at Date' field to any date. You can calculate how old you'll be on your next birthday, at retirement, or how old you were on a specific historical date.
This happens when the end date falls on the same day of the month as your birthday. You've completed full months with no leftover days.
Total days is the raw difference between the two dates in days — it counts every calendar day including leap years. It's more accurate than multiplying years × 365.
Yes. If you were born on Feb 29, the calculator correctly handles years where Feb 29 doesn't exist by treating March 1 as the equivalent date for non-leap years.
No. All calculations happen entirely in your browser using JavaScript. Nothing is sent to a server and nothing is saved after you close the tab.
Total hours appear automatically in the stats grid below the calculator. To also see total minutes, make sure 'Detailed breakdown' is enabled in Settings.
