Age Calculator
Calculate your exact age in years, months, weeks, days, hours, and minutes from birth date.
Age Breakdown
- In months
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- In weeks
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- In hours
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- Born on a
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- Next birthday
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Calendars make this harder than it looks
Age in years is the difference between two dates, adjusted for whether the birthday has occurred yet this year. The complications are all calendar artefacts: months have different lengths, leap years add a day every four years except centuries not divisible by 400, and "one month later" is genuinely ambiguous — 31 January plus one month lands on 28 February in most implementations, and the reverse operation does not return you to 31 January.
People born on 29 February are the standard edge case. In non-leap years, jurisdictions and software differ over whether the legal birthday falls on 28 February or 1 March, which matters for things like coming of age. Most date libraries pick one and are consistent; the law is not always consistent with them.
Counting conventions vary culturally too. The Western system counts completed years, so a newborn is 0. East Asian age reckoning has traditionally counted a baby as 1 at birth with the number incrementing at new year, which can make someone up to two years "older" than their Western age. When a precise figure matters — legal, medical, or official — count in whole days between the two dates and convert, rather than relying on month arithmetic.
Frequently asked questions
How is exact age calculated?
Exact age is calculated by finding the difference between your date of birth and the target comparison date.
How is exact age calculated?
By subtracting calendar components with borrowing: take the difference in years, then months, then days, borrowing from the next unit up when a value goes negative. This is why age in years, months and days is not simply the total day count divided by 365 - months have different lengths, so the two answers legitimately differ.
How is the age of someone born on 29 February handled?
In non-leap years the anniversary is conventionally treated as 28 February in most legal systems, though some jurisdictions use 1 March. Since the birthday exists only every four years, the practical rule is that the person turns a year older once the equivalent calendar point has passed.
Why does my age in days not match my age in years times 365?
Because of leap days. Someone who is 30 has lived through seven or eight 29 Februaries, so their day count exceeds 30 x 365 by about a week. Over a lifetime the discrepancy grows to more than two weeks, which matters whenever a day count is used for a legal or medical threshold.