Age Calculator
Calculate your exact age in years, months, days — and fun extras like days lived, heartbeats, and next birthday.
Your age sounds like the simplest number in the world until you need it precisely — in years, months, and days — for a form, a milestone, or just curiosity. This calculator takes your birth date and today's date and returns your exact age, correctly handling the uneven lengths of months and the leap years that trip up manual counting.
It is handy for filling in official documents that ask for an exact age, tracking a baby's age week by week, counting down to a landmark birthday, checking eligibility cut-offs for schools or benefits, or settling the friendly debate about who is older by how many days. Because it works to the day rather than rounding to the nearest year, it gives you a precise, trustworthy figure rather than a rough estimate.
Plug in some numbers —
we'll crunch.
How to use
- 1Enter your date of birth.
- 2Optionally change the 'as of' date to calculate age at a specific point in time.
- 3Leave 'as of' blank to use today's date.
- 4See your exact age and fun lifetime statistics.
How it works
Calculating an exact age is more than subtracting birth year from current year, because that ignores whether your birthday has happened yet this year. The tool compares the full dates: it subtracts the years, then adjusts the months and days, borrowing where needed — much like long subtraction — so that, for example, a birthday next week leaves you a year younger than the naive year difference suggests.
Leap years add a wrinkle. People born on February 29 have a birthday only once every four years, and month-length differences (a 'month' can be 28 to 31 days) mean the day count has to be handled carefully. The calculator resolves these by working from the actual calendar, which is why it can also tell you your age in total days, weeks, or months — each just a different way of counting the same span.
Worked examples
Exact age for a form
Born on August 15, 1990, with today being June 10, 2026.
- Years: 2026 − 1990 = 36, but the August birthday hasn't occurred yet in 2026.
- So subtract one: 35 years.
- Then count the months and days from last August to today.
You are 35 years, 9 months, and about 26 days old — not 36, because your birthday is still two months away. This is exactly the off-by-one a naive year subtraction gets wrong.
A baby's age in weeks
A baby born on April 1, 2026, checked on June 10, 2026.
- Days in April after the 1st: 29. All of May: 31. Plus 10 in June.
- Total = 70 days.
- Divide by 7: 10 weeks.
The baby is exactly 70 days, or 10 weeks, old. Parents and pediatricians often track early development in weeks, where this day-level precision genuinely matters.
Tips & common mistakes
Be clear about whether your birthday has already passed this year — that single fact decides your year count and is the most common manual-counting error. The calculator handles it automatically by comparing the full dates rather than just the years.
Different cultures and systems count age differently. The international standard counts completed years from birth, but some traditions count differently (a few consider you 'one' at birth). For official purposes, the completed-years figure this tool gives is the standard, but be aware the answer can differ if a form uses another convention.
If you need age as of a specific past or future date — eligibility on the first day of a school term, say, rather than today — calculate to that date, not the current one. Many cut-offs hinge on your age on an exact day, so using today's date can give a misleading answer. When precision drives a real decision, double-check the reference date the form or rule actually requires.
Frequently asked questions
Last reviewed: June 2026
About this calculator
Calculate your exact age in years, months, days — and fun extras like days lived, heartbeats, and next birthday.