Find your exact age in years, months and days from your date of birth.
Enter a date of birth and this returns exact age in years, months and days, along with totals in weeks, days and hours. The calculation counts completed years — the convention used almost everywhere for legal and everyday purposes. You are 29 until the moment your 30th birthday arrives, not from the day you enter your thirtieth year.
Someone born on 14 March 1990, calculated on 6 August 2026:
Note the order of operations: years first, then whole months from the anniversary, then remaining days. Working in any other order gives different answers.
Months have between 28 and 31 days, so "one month later" has no universal definition. The convention here — and in most software — keeps the day number and advances the month, clamping to the last valid day when it does not exist. So 31 January plus one month is 28 February.
The consequence is that the operation is not reversible. Add a month to 31 January and you get 28 February; subtract a month and you get 28 January, not 31 January. This is why the plain day count is the figure to use for anything precise, and the years-months-days breakdown is best understood as a human-readable approximation.
Someone born on a leap day has a birthday that exists only every fourth year. Jurisdictions differ on which date they legally turn a year older in a common year:
Both are defensible and the difference matters for things like the exact day someone reaches the legal drinking age or qualifies for a pension. This calculator uses 1 March in common years. If a legal deadline depends on it, check the rule in the relevant jurisdiction rather than relying on any calculator.
The completed-years convention is not universal. In the traditional East Asian age reckoning still used informally in parts of Korea and elsewhere, a person is one year old at birth and gains a year at the lunar new year rather than on their birthday — which can make someone two years older than their international age. South Korea formally standardised on the international system in June 2023, though the traditional count persists in conversation.
In some legal and insurance contexts, age nearest birthday is used instead: someone 30 years and 7 months is treated as 31. Life insurance pricing frequently works this way, which is why a policy quote can jump on a date that is not your birthday.
| Age in years | Days | Hours | Approximate heartbeats |
|---|---|---|---|
| 10 | 3,653 | 87,672 | 368 million |
| 25 | 9,131 | 219,144 | 920 million |
| 40 | 14,610 | 350,640 | 1.47 billion |
| 65 | 23,741 | 569,784 | 2.39 billion |
Day counts here use the Gregorian average of 365.2425 days per year, which accounts for leap years including the century rule.
The calculation uses your device's local date. Someone born in one time zone and calculating their age in another can see a result differing by a day near midnight, since the birth date itself was recorded in local time at the place of birth. For everyday use this is irrelevant; for a legal deadline falling on a birthday, the governing jurisdiction's time zone is what counts.
By completed years first, then whole months from the most recent birthday, then remaining days. You remain a given age until your next birthday actually arrives, which is the convention used legally almost everywhere.
It depends on jurisdiction. England and Wales treat it as 28 February in common years; the United States and several others treat it as 1 March. This calculator uses 1 March. Check local law if a legal threshold depends on it.
Because months vary from 28 to 31 days, so "one month" is not a fixed quantity. The calculation advances the month while keeping the day number, clamping where that date does not exist. Use the total day count when precision matters.
Yes. Every 29 February in the period is counted, following the rule that leap years are divisible by 4 except century years not divisible by 400.
Traditional East Asian reckoning counts a person as one year old at birth and adds a year at the new year rather than on their birthday, which can put it two years ahead. South Korea adopted the international system officially in 2023.