Calculate your exact age in years, months and days — or the difference between any two dates. See your age in total weeks, hours, minutes and seconds, plus a live countdown to your next birthday. Free, no signup, runs in your browser.
An age calculator is a tool that tells you your exact age — or the gap between any two dates — broken down into years, months and days. While most people roughly know their age in years, computing the precise number of months, weeks, hours and minutes requires careful date arithmetic that accounts for variable month lengths, leap years and the Gregorian calendar's quirks. This free online age calculator handles all of that automatically, runs entirely in your browser, and even refreshes the seconds counter in real time.
The fundamental formula is straightforward: subtract the start date from the end date, then express the difference in calendar units. The challenge is that February has 28 or 29 days, other months alternate between 30 and 31, and "one month later" is a stretchy concept. Standard age-counting follows the convention that February 28 in a non-leap year equals "one year after February 29 in a leap year". This calculator implements the convention used by birthday certificates, insurance forms and legal age verification.
To calculate your age manually, follow this algorithm — which is exactly what this calculator does under the hood:
For example: if you were born on January 8, 2000, and today is May 20, 2026 — you are 26 years, 4 months and 12 days old. The hours-and-minutes view simply converts the total millisecond delta into smaller units.
The calculator has three modes that cover the most common date-math questions:
The "months" and "weeks" totals shown in the stat tiles are approximations because months are not equal in length. A 30-year-old has lived through about 360 months — but the exact number depends on how many of those years included Februaries and which months had 31 days. For perfect precision, rely on the years/months/days breakdown in the hero number. The total days, hours, minutes and seconds are mathematically exact (derived from the timestamp difference).
Age calculators are used far beyond satisfying curiosity. Common scenarios include:
The Gregorian calendar used worldwide is a refinement of the Julian calendar introduced by Pope Gregory XIII in 1582. To keep the calendar year aligned with the Earth's orbit (~365.2422 days), it adds a leap day to February every four years — except for century years not divisible by 400. That's why 2000 was a leap year but 1900 and 2100 are not. Months of 30 and 31 days alternate imperfectly because the calendar evolved from Roman political decisions, not pure math: August was given 31 days so it wouldn't seem shorter than July, named after Julius Caesar. Every accurate age calculator must account for these quirks — which is exactly why subtracting dates by hand is error-prone.
26 years, 4 months, 12 days
≈ 317 months · 1,381 weeks · 9,629 days · 231,096 hours250 years, 0 months, 0 days
Exactly 91,311 days · 2,191,464 hoursToday: May 20, 2026
Next birthday: March 15, 2027 (Monday)
299 days to go — you'll turn one year olderAge is the difference between the birth date and a reference date (usually today), expressed in years, months and days. The standard algorithm subtracts years, then months, then days — borrowing from the next-larger unit when needed. This calculator follows the convention used by official forms: if someone was born on February 29, their birthday is counted as February 28 in non-leap years.
The simplest formulation: years = endYear − startYear, then adjust by subtracting 1 if the current month/day is before the birth month/day. For months and days, subtract them directly and borrow as needed when the result is negative. The total in milliseconds is endDate.getTime() − startDate.getTime(), which is mathematically exact regardless of calendar quirks.
Use the "Age now" mode and look at the birthday card below the stats. It shows exactly how many days remain until your next birthday and which weekday it falls on. The countdown updates every time you reload the page.
Yes. Switch to "Date difference" mode and enter both birth dates. The tool computes the exact gap in years, months and days. You can also use it to find anniversaries, time since an event, or duration of any project.
Yes. Use "Age at date" mode. Enter your birth date and the target date (past or future). This is useful for eligibility checks, retirement planning, legal forms or just curiosity about how old you were at a specific moment.
Months are not equal in length (28, 30 or 31 days), and weeks don't fit cleanly into months. The years/months/days breakdown is the official calendar count. The total months, weeks and days shown in the stat tiles are derived from the millisecond difference and rounded — they're approximations useful for context but the calendar count is the authoritative answer.
Leap years are handled automatically by JavaScript's native Date object, which knows that years divisible by 4 (but not by 100, unless also by 400) include February 29. If you were born on February 29, your birthday is treated as February 28 in non-leap years — the convention used by insurance, legal and government forms worldwide.
Yes on both. The math is exact for the calendar breakdown and for the millisecond totals. Privacy: this tool runs entirely in your browser. Your birth date and any dates you enter are never sent to any server. Values are saved locally so you can come back later, with no signup or tracking.