Age Calculator
Work out your exact age in years, months and days from your date of birth — plus your age in total weeks and days, and a countdown to your next birthday.
Age calculator
Enter a date of birth to get an exact age.
Runs entirely in your browser. Nothing you enter is saved or sent anywhere.
How the age calculator works
Working out an exact age looks simple but is fiddly, because months have different lengths and leap years add an extra day every four years. This calculator compares two real calendar dates — your date of birth and the date you want your age on — and counts whole years, then whole months, then the leftover days, borrowing from the previous month where needed.
Your age in years, months and days is the gap between your birth date and today. Someone born on 15 March 2000 would be exactly 26 years and a few days old in mid-2026 — the tool also shows the total in days, weeks and months.
Different ways to express your age
| Measure | What it means |
|---|---|
| Years, months, days | The everyday way we state age |
| Total months | Useful for babies and toddlers |
| Total weeks | Common in pregnancy and infancy |
| Total days | Exact, leap-year-safe count |
Why exact age matters
An exact age is needed for all sorts of things — school year groups, pension and State Pension age, insurance, visa applications and legal thresholds. Because this tool lets you set any "age at" date, you can check how old you (or a child) will be on an exact future date, such as the first day of a school term or your State Pension age. To measure a plain gap between two dates instead, use our days between dates calculator.
Frequently asked questions
How do I calculate my exact age?
Enter your date of birth and the calculator subtracts it from today's date, accounting for the different lengths of months and any leap years, to give your exact age in years, months and days.
How is age in years, months and days worked out?
The tool counts whole years since your birth date, then the whole months since your last birthday, then the remaining days. It 'borrows' from the previous month when the day-of-month has not yet been reached, just like long subtraction.
Does the age calculator account for leap years?
Yes. Because it compares actual calendar dates, leap days are counted automatically. The age in total days will be exact whether or not your life has spanned a 29 February.
Can I work out my age on a future or past date?
Yes. Change the 'age at' date to any date you like — a future birthday, a past anniversary or an exam date — and the calculator shows how old you were, or will be, on that day.
How many days until my next birthday?
The calculator finds your next birthday from the 'age at' date and counts the days remaining, so you always know exactly how long until you turn another year older.