Leaplings are rare
Born on 29 February? You’re in a club of roughly 1 in 1,461 birthdays. Some leaplings celebrate on both 28 Feb and 1 Mar.
Calendar quirks
Age Calculator — Years, Months & Days
Inputs
Results
Select dates and press Calculate Age.
Tip: Use Tab to move across inputs. Your data never leaves your device.
How the Age Calculator Works
This privacy-first age calculator returns an exact breakdown of age in years, months, and days, a countdown to the next birthday, and your age on any specific date. It runs entirely in your browser (client-side JavaScript), so your dates never leave your device.
Start by selecting your Date of Birth. If you leave the Target Date empty, the calculator uses today’s date, making it a quick “How old am I?” tool. To check an age at a past or future moment—such as a filing date, school start, or compliance cut-off—choose a Target Date and click Calculate Age. The algorithm computes differences in a calendar-aware way: it accounts for varying month lengths (28–31 days) and leap years when rolling through months and years.
When the Target Date is today, you’ll also see time until your next birthday. For birthdays on 29 February, the next birthday in non-leap years is treated as 28 February by default, a widely used convention for anniversary calculations.
Typical uses include education and HR onboarding (age eligibility), sports or event categories, visa and immigration paperwork, pension and benefits planning, and milestone tracking. Outputs are presented in clear language and can be copied directly into forms or spreadsheets.
Tip: you can adjust either the Date of Birth or the Target Date and immediately re-run a scenario—handy for “what-if” checks around cut-off dates.
Age Calculator: FAQs
Does this calculator handle leap years and different month lengths?
Yes. The calculator accounts for leap years and varying month lengths when computing years, months, and days.
Can I calculate age on a past or future date?
Yes. Choose a Target Date to see the age on any past or future date instead of today.
Is my data private?
Yes. All calculations run locally in your browser; no data is uploaded or stored on a server.
What happens with birthdays on 29 February?
For non-leap years, the next birthday is treated as 28 February by default (some organisations prefer 1 March).
5 Fun Facts about Age & Birthdays
You’ve had millions of heartbeats
An average adult heart beats about 115,000 times per day—that’s roughly 42 million beats every year of your age.
Body math
Age on Mars
A Martian year is ~687 Earth days. Divide your age in days by 687 to find your Martian birthdays (you’re younger there).
Space twist
Population peak day
Globally, more people are born in September than any other month—handy for predicting cake demand at the office.
Birthday trends
“Official age” differs
South Korea historically added a year at birth and on New Year’s Day; as of 2023, it aligns with international counting—age can be policy-dependent.
Cultural twist