Age Calculator
Your exact age isn't simply the difference between two calendar years, the Gregorian calendar makes it more complex. The algorithm counts complete years first, then remaining months, then remaining days, accounting for variable month lengths (28–31 days) and leap years that insert February 29 every four years (except century years not divisible by 400). Knowing your precise age to the day matters for school enrolment cutoffs (most Australian states use a 30 April or 1 July cutoff for Prep/Kindergarten), sports age categories like Under-14 competitions, insurance eligibility windows, superannuation preservation age calculations, and historical research. This calculator shows your age in years, months, days, total weeks, and total days, plus a live countdown to your next birthday and the year each major milestone (18, 21, 30, 40, 50, 65) falls on.
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Frequently Asked Questions
How does the age calculator work?
Enter your birth date and the calculator subtracts it from today's date (or any date you choose) to find the exact age in years, months, and days. It handles all calendar complexities automatically, including leap years, variable month lengths (some months have 30 days, others have 31, and February has 28 or 29), and the exact day you were born. The result is accurate to the day, with no rounding or estimation involved.
How do I calculate my age in months and days?
Once you know your age in years, the remaining months and days are counted from your last birthday. The calculator first counts full years, then works out how many full months have passed since your last birthday, then how many days have passed since the start of the current month. For example, if you were born on 15 March 1990 and today's date is 22 June 2024, you are exactly 34 years, 3 months, and 7 days old. The total number of days is also shown, which you can divide by 7 to get your age in weeks.
Does the calculator account for leap years?
Yes. The calculation uses the actual Gregorian calendar including leap years, which add an extra day every four years (except century years not divisible by 400, like 1900 and 2100). February 29 is a real date that occurs every four years, and people born on that date technically have a birthday only every four years in non-leap years. Without leap year handling, anyone calculating age would gradually drift from the true date over time - after 100 years, you'd be off by about 25 days.
Can I calculate someone's age on a past date?
Yes. Enter the birth date and set 'calculate age on' to any past or future date to see how old someone was or will be on that specific date. This is useful for school enrolment cutoff dates (many countries use 1 January or 1 September cutoffs), sports age categories (like Under-14 sports), insurance policy dates, historical research, working out eligibility for events that happened before today, or simply satisfying curiosity about historical figures' ages at important moments.
How accurate is this age calculator?
This calculator is accurate to the day. It uses the standard Gregorian calendar algorithm to compute the exact interval between two dates, accounting for all month lengths and leap year rules. It handles edge cases like people born on 29 February, the varying lengths of months, and century year exceptions correctly. The next birthday countdown also updates in real time as each day passes, showing you exactly how many days remain until your next birthday.
How old am I in weeks?
Multiply your total days by 7 to get weeks. As a rough approximation, your age in weeks is roughly your age in years multiplied by 52, plus the remaining days divided by 7, minus roughly one day per leap year you've lived through. For example, a 25-year-old who was born on a non-leap year has lived approximately 1,300 weeks - though the exact number depends on their birth date and the current date. The calculator shows your exact total weeks, not just an approximation.