Age Calculator
Find your exact age in years, months, days, hours, minutes, and seconds — and how many days until your next birthday.
Your age
Age in different units
Next birthday
How age is calculated, exactly
Your age in years is the number of complete years you've been alive. The math sounds obvious — current year minus birth year — but it's slightly more nuanced because we haven't reached your birthday yet most of the time. So we take current year minus birth year, then subtract one if your birthday hasn't happened this calendar year.
For exact months and days, we walk the calendar from your date of birth to the target date. This calculator handles the messy parts: months have different numbers of days, leap years add a Feb 29, and the “turn of a month” happens differently depending on the start date. The result is the same answer your DMV, employer, or doctor would calculate — just instant.
Why total seconds is so much bigger than you'd guess
A 30-year-old has lived approximately 946 million seconds. Even a 10-year-old has lived 315 million seconds. The numbers feel surreal because we don't experience time at that resolution — but every one of those seconds was real. The calculator also shows totals in days, weeks, hours, and minutes — useful for fitness tracking, programming time-since calculations, or just getting a sense of scale.
Common age milestones in the US
Many legal rights and obligations attach to specific ages. The calculator's “Age at date” mode is useful for planning around these — e.g., “On what date will I turn 65?”
- Age 16 — driver's license eligibility in most states (some allow learner's permits at 14–15).
- Age 18 — voting, contract-signing, military enlistment, legal adult.
- Age 21 — alcohol purchase, casino gambling in most states.
- Age 26 — last year on a parent's health insurance under the ACA.
- Age 50 — catch-up contributions allowed for 401(k) and IRA.
- Age 59½ — penalty-free withdrawals from traditional retirement accounts.
- Age 62 — earliest age to claim Social Security retirement benefits (with reduction).
- Age 65 — Medicare eligibility.
- Age 67 — full Social Security retirement age (for those born 1960 or later).
- Age 70 — maximum delayed retirement credit for Social Security.
- Age 73 — required minimum distributions (RMDs) from traditional 401(k) and IRA.
Calculating age between any two dates
The calculator's “Age at date” field defaults to today, but you can change it to any date — past or future. Useful cases:
- How old was I at a specific event? Set the target to the date of the event.
- How old will I be at retirement? Set the target to your planned retirement date.
- What's the age difference between two people? Use one person's birth date and the other's as the “target” date.
- Was I 18 yet on this date? Useful for resolving any ambiguity in legal documents.
Leap years and Feb 29 birthdays
Leap years happen every 4 years (with the exception that years divisible by 100 but not 400 are not leap years — 2000 was, 2100 won't be). They add a Feb 29.
People born on Feb 29 (“leaplings”) only have a literal birthday every 4 years. Different jurisdictions handle this differently for legal purposes — some treat Feb 28 as the birthday in non-leap years, others use Mar 1. Our calculator counts elapsed time precisely, so a Feb 29 baby reaches their first “year” on Feb 28 of the year after birth (or Mar 1, depending on the year — JavaScript's date math handles this consistently).
Age conventions around the world
Most of the world uses the system this calculator implements: age = completed years since birth. A few traditions count differently:
- East Asian age (traditional, less common today) — you start at age 1 at birth and add a year each Lunar New Year. So a person could be “2 years old” in this system while only being a few months old in Western reckoning. South Korea legally moved to the international system in 2023.
- Insurance age (US life insurance, dental) — sometimes rounds to the nearest birthday rather than the most recent. A 35-year-old who is 6+ months past their birthday is “age 36” for premium calculations.
- Astrological age — culturally varies. The calculator just gives you the count; what you do with it is up to you.
Privacy: your dates never leave the page
All calculations happen in your browser using JavaScript. We don't log, store, or send your birth date anywhere — there's no server-side processing of dates. You can use the calculator with sensitive HR data, family records, or anything you wouldn't want sitting in someone else's database.
Need related tools? Try our Date Calculatorfor date differences without the “age” framing, or the Pregnancy Due Date Calculator for pregnancy-specific dating.