Age Calculator
Precisely calculate age from birth date with real-time countdown.
Related guide
BMI, Age and Date Calculators: Which Numbers to Trust, and When
The BMI page classifies the rounded number, not the real one. The age page anchors its counters to UTC midnight and keeps ticking after you clear the box. The date page counts days from local midnight, so a clock change can cost you one. Every figure below was measured on the pages themselves.
What the four numbers mean
Pick a date of birth and the calculator returns four figures at once: your age in whole years, the total number of months, the total number of days, and the total number of hours you have been alive.
The big number at the top is the figure you would give if someone asked how old you are. The three smaller ones are running totals — they are useful for curiosity and for forms that ask for "age in months" (which many childcare and medical questionnaires do), not for legal documents.
How the age in years is calculated
The calculator subtracts your birth year from the current year, then corrects the result: if this year's birthday has not arrived yet, it subtracts one. So the number changes on your birthday, not on 1 January, and it matches the answer you would work out by hand.
Totals are measured in complete 24-hour periods from the start of the date you entered, so the day itself counts as zero rather than one. The month figure uses an average month of 30.44 days (365.25 ÷ 12), which is why it can differ by a day or two from counting calendar months one by one.
The birthday countdown
The last line counts down to your next birthday in days, hours, minutes and seconds and updates once a second. It always targets the same month and day as your date of birth in the current year, rolling forward to next year once the date has passed.
One edge case worth knowing: if you were born on 29 February, the countdown points at 1 March in non-leap years, because that is the nearest valid date after the missing 29 February.
FAQ
Is my date of birth sent anywhere?
No. The calculation runs entirely in your browser with JavaScript — the date never leaves your device. You can confirm this by opening your browser's network panel while using the page.
Can I calculate the age of a baby in months?
Yes, that is what the total-months figure is for. Enter the birth date and read the months total — a 7-month-old baby shows as 7. Note that the figure uses an average month of 30.44 days, so if you need the exact age for a vaccination schedule or a developmental check, count calendar months on a calendar instead.
What happens if I enter a future date?
The calculator will not produce a negative age. It shows "Not born yet" instead, so you can use a future date for an unborn child without getting nonsense numbers.
Why does the month total not match my age × 12?
Because a year is slightly longer than 12 average months: 12 × 30.44 = 365.28 days. The tool multiplies the elapsed time by that average, so over long spans the month total drifts a little from a strict calendar count.
Does it handle leap years correctly?
The age in years is calendar-based, so 29 February birthdays age normally: someone born on 29 February 2000 is 26 years old on 28 February 2026 and 27 on 1 March 2026, the same convention most legal systems use. The birthday countdown targets 1 March in non-leap years.
Can I use this for official paperwork?
Use it to check your arithmetic, not as the source of record. Official documents should use the age as defined by the issuing authority, because some jurisdictions count the birth day itself and others do not.