Age Calculator — Work Out Your Exact Age in Years, Months and Days
Calculate exact age between any two dates, plus totals in months, weeks, days and hours.
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| Day of the week you were born | — |
| Next birthday falls on | — |
| Heartbeats (approx, at 70 bpm) | — |
| Breaths taken (approx, at 16/min) | — |
| Full moons seen (approx) | — |
Enter a date of birth to get an exact age in years, months and days, along with the total in months, weeks, days and hours, the day of the week you were born, and how long until the next birthday.
How to use Age Calculator
- Enter the date of birth.
- Set the “age at” date — it defaults to today, but you can set any date to work out age at a future or past point.
- Read the breakdown below.
How calendar age is counted
Age is counted by borrowing across calendar boundaries, not by dividing elapsed days by 365.25. If the day of the month has not been reached yet, we borrow days from the previous month and reduce the month count; if the month has not been reached, we borrow from the year. This is how people actually state their age, and it handles leap years correctly without approximation.
Leap year birthdays
Anyone born on 29 February has a birthday only in leap years. Most jurisdictions treat 1 March as the legal birthday in common years, though some use 28 February. This calculator counts the date as reached on 1 March.
Age reckoning is not universal
The system used here is the international standard, where you are 0 years old at birth and turn 1 on your first birthday. Some traditional East Asian systems count a newborn as 1 and add a year at the lunar new year rather than on the birthday, which can put a person one or two years older than their international age. South Korea officially moved to the international system in June 2023.
Frequently asked questions
How is age calculated exactly?
By borrowing across calendar boundaries rather than dividing days by 365.25. This handles leap years correctly and matches how people actually state their age.
What about a 29 February birthday?
In common years most jurisdictions treat 1 March as the legal birthday, and that is what this calculator uses. Some places use 28 February instead.
Can I calculate age at a past or future date?
Yes. Change the "age at date" field to any date — useful for working out how old someone was at an event, or will be on a future one.