Age Calculator

Age Calculator works out how old someone is today as a full calendar breakdown of years, months and days, and also as a running total of days. Enter a birth date in YYYY-MM-DD form and it compares it with your device's current date, borrowing from the month and the year where the day or month count would otherwise go negative — so a 1990-vintage date viewed today returns an exact years-months-days figure rather than an approximation.

The calendar breakdown and the total-day count answer slightly different questions. The years-months-days line is how people normally state an age; the total-days line is the raw elapsed count, which is what you want for a precise record. Both are derived from the same two dates, so they always agree with each other.

Because it reads the clock on the machine it runs on, the answer depends on your local date and time zone. Two people in different zones entering the same birth date at the same instant can see a one-day difference at a birthday boundary. And if the birth date lies in the future, the calculation still returns a figure — so check the input rather than trusting a nonsensical result.

There is one input and no settings beside it. A second date cannot be supplied, so age on a particular past or future date cannot be asked for — the calculation is always against the present moment — and no date-time is accepted, only a plain calendar date, so a birth time plays no part in the result. Nothing about the answer is contextualised: the tool does not report the next birthday, the day of the week the person was born on, the total in weeks or months, or the zodiac and life-stage figures some age calculators add. Because the arithmetic borrows from the preceding month as it counts down, the years-months-days line follows calendar convention rather than a simple division, which is worth knowing when comparing against a tool that divides elapsed days by thirty.