Everyday
Age calculator
Exact age between two dates, counted the way birthdays are actually counted — whole months first, then the remaining days.
How age is counted here
Age is worked out by counting calendar parts rather than dividing total days by 365. The calculator finds the largest number of whole months that fit between the two dates, converts that to years and months, and then counts the days left over. Where a month is shorter than the birth day — 31 January plus one month, for instance — the anniversary clamps to the last day of that month.
This is the method used almost everywhere for legal and everyday purposes, and it's why someone can be "23 years, 0 months and 30 days" old: the final month simply hasn't completed.
The leap year problem
Dividing days by 365 drifts. Over 40 years it loses roughly ten days, because a leap year is inserted every four years — except in century years not divisible by 400. The year 2000 was a leap year; 1900 was not, and 2100 will not be. Counting by calendar parts avoids the drift entirely, so this calculator does that instead.
People born on 29 February are a genuine edge case. There is no legal consensus across countries about whether their birthday falls on 28 February or 1 March in common years. This calculator treats 28 February as the day the year completes in a common year, which is the convention most software uses, but check your local rules if it matters for a document.
Common questions
Can I calculate age between two past dates?
Yes. The second field defaults to today, but you can set it to any date — useful for working out how old someone was at a particular event, or the gap between two dates for a form.
Why don't the total days match years × 365?
Because of leap days. The total days figure is a true count between the two dates, so it will be higher than a 365-a-year estimate by roughly one day for every four years elapsed.
Is anything I enter stored?
No. The calculation runs entirely in your browser. The dates aren't sent to a server and aren't saved anywhere.