Age Calculator

An age calculator works out exact age from a date of birth. Someone born on 15 May 1990 is 36 years, 5 months and 2 days old on 17 October 2026, which is 437 months or 13,304 days. Pick any date to find an age in the past or future.

By Editorial Team Updated 19 Oct 2026

How to use this date of birth calculator

Enter the date of birth. Tap the date field and pick the day, month and year someone was born.
Choose the date to measure to. It defaults to today. Change it to find someone’s age on a past or future date, such as an exam deadline or a school start date.
Read the result. The age updates instantly in years, months and days, with totals and the next birthday underneath.

How old am I? How age is counted

In most of the world, including the UK, US and Europe, age is counted in completed years: you are 0 at birth and gain a year on each birthday. To get the months and days, the calculator counts whole calendar months from your last birthday, then the days left over.

Months have different lengths, so “1 month” can mean 28, 29, 30 or 31 days. When a month is shorter than your birth date (for example, born on the 31st), the calculator counts the last day of the shorter month as the monthly anniversary. That is the same convention used by most legal and medical systems.

Chronological age calculator for school, health and forms

Chronological age simply means the time since birth, as opposed to developmental, biological or “corrected” age. It is used for:

School admissions and year groups, which often depend on age on a fixed date such as 31 August (England) or 1 September (many US states).
Child development checks and test scoring, where examiners need age in years and months, for example 7 years 4 months.
Eligibility for licences, pensions, insurance and retirement benefits.

For babies born before 37 weeks, health visitors and paediatricians often use a corrected age (chronological age minus the weeks born early) until about age 2. This calculator shows chronological age only.

Age in months, weeks and days

Ages of babies and toddlers are usually given in months, and some people like to celebrate milestones such as 10,000 days. The calculator shows every unit at once:

Born	On 17 October 2026	Total months	Total days
15 May 1990	36 years, 5 months, 2 days	437	13,304
29 February 2000	26 years, 7 months, 18 days	319	9,727
1 August 2010	16 years, 2 months, 16 days	194	5,921

Total weeks and hours are also listed in the table under the result.

Leap-year birthdays

If you were born on 29 February, your birthday only falls on the real date once every four years. In common years this calculator marks your birthday on 28 February, so your age changes at the end of February. Legal rules vary: in England and Wales you legally reach a new age on 1 March in a common year. Check the rules that apply if the exact day matters, for example for a driving licence or alcohol purchase.

Fun facts from your date of birth

Day of the week: the calculator tells you whether you were born on a Monday, a Saturday or any other day.
10,000 days: you reach 10,000 days old at about 27 years and 4 months.
Next birthday: see the date, the weekday it falls on and how many days are left.

Age calculator FAQs

How do I calculate my age?

Subtract your birth year from the current year, then take one off if your birthday has not happened yet this year. For months and days, count whole months since your last birthday and then the remaining days, or let the calculator do it.

How do I find someone's age on a specific date?

Change the second date from today to the date you need, for example a deadline or an event, and the age updates.

Does the calculator account for leap years?

Yes. Total days include every 29 February in the period, and monthly anniversaries use the actual length of each month.

Is my date of birth stored?

No. The calculation runs in your browser and nothing you enter is sent to our servers.

Why does East Asian age differ?

Traditional Korean and some Chinese age counting started at 1 at birth and added a year at the new year. South Korea officially switched to international age in 2023. This calculator uses international age.

Sources and methodology

Age is counted in whole calendar months from the date of birth, clamping to the last day of shorter months, then remaining days. Total days are the exact number of days between the two dates. Decimal years divide total days by 365.2425 (the average Gregorian year). Leap-day birthdays fall on 28 February in common years. All example figures were produced by this calculator.