Age Calculator
Enter a date of birth to get your exact age in years, months and days, the totals in months and days, and a countdown to your next birthday.
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Age
{{ result.years }}years
- Total months
- {{ result.totalMonths }}
- Total days
- {{ result.totalDays }}
- Next birthday
- {{ result.nextBirthday }}
- Days until next birthday
- {{ result.daysUntilNextBirthday }}
Enter a date of birth above to calculate the exact age.
Your date of birth is used only in your browser to calculate the result. It is never uploaded to a server.
How age is calculated
The years, months and days are calendar-exact — not an average of 30.44 days per month. The tool counts whole calendar months between the two dates, then whatever days are left over, borrowing a month or a year at the boundary exactly the way you would counting on a calendar by hand.
A birthday on 29 February is treated as landing on 28 February in a non-leap year, so "next birthday" always resolves to a real, existing date.
Why the day count sometimes surprises people
Someone born on 31 January turning an anniversary in a 30-day month doesn't lose a day of age — the tool borrows the correct number of days from the actual calendar month involved, so the count stays exact across every combination of month lengths and leap years.
Frequently asked questions
How is the age calculated so precisely?
The years, months and days are calendar-exact, using the same "borrow a month, borrow a year" method you'd use counting on a calendar by hand — not an average of 30.44 days per month, which would drift over time.
What happens with a birthday on 29 February?
In a year that isn't a leap year, the anniversary is treated as 28 February — the common convention — so "next birthday" always lands on a real date.
Can I calculate age as of a date other than today?
Yes. Set the "Calculate age as of" field to any date on or after the date of birth — useful for eligibility rules tied to a specific cutoff date rather than today.
Why do total months and years/months/days not always match a simple multiplication?
Total months counts every whole calendar month elapsed (years × 12 + months), while the years/months/days breakdown also carries a remainder of days that a total-months figure alone doesn't show.
Is my date of birth sent anywhere?
No. The calculation runs entirely in your browser using JavaScript. Nothing is transmitted to a server.