A live age that ticks every second, anchored to your real time of birth if you provide it — not a static snapshot rounded to midnight.
Age Calculator
Enter your date of birth to see your exact age in years, months and days — plus a live ticking age, a next-birthday countdown, the weekday you were born, your age in Korean and Chinese counting, your zodiac signs and the milestone dates worth celebrating.
Without a birth time, totals assume you were born at midnight (00:00).
How old am I if I was born in…
How to use it
- Enter your date of birth. The result appears instantly — no button to press.
- Optionally add your time of birth for second-precise totals, and change the "age on date" field to compute your age on any past or future date.
- Scroll down for cultural age systems, zodiac signs, milestone dates, fun equivalents, and use the copy or share buttons to keep the result.
How this age calculator works
Your age is calculated the calendar-exact way: full years to your last birthday, then full months to the same day of the month, then the remaining days. When a month is shorter than your birth day-of-month (born on the 31st, checking on 1 March), the calculator counts the month boundary on the last available day, which is the same convention used by calculator conventions in most legal contexts. The result is never approximated with 30.44-day average months.
Totals in hours, minutes and seconds assume you were born at midnight unless you enter your time of birth. Add the optional birth time and the live counter ticks from the actual moment, so "when do I turn exactly one billion seconds old" gets a real answer, not a date rounded to midnight.
Everything runs in your browser: no dates are sent to a server, and the calculation updates instantly as you type. Set the "age on date" field to any past or future date to answer questions like "how old was I when…" or "how old will I be in 2050".
Two people can disagree about an age in months and both be right. Born on 31 January, how old are you on 1 March? If you count "31 January to 28 February" as a month, the answer is 1 month 1 day; if you count month-ends to month-ends, it is exactly 1 month. Spreadsheet functions, databases and programming languages each pick a different convention, which is why Excel’s DATEDIF, PostgreSQL’s age() and an online calculator can produce three different answers from the same two dates. This calculator uses the anniversary method — months are counted to the same day of the month, clamped to the last day when the target month is shorter — and says so, instead of hiding the convention.
Time of birth and time zone matter more than most calculators admit. If you were born at 11 p.m. in Sydney and now live in Lisbon, the moment you turn exactly 30 — measured in elapsed time — is not midnight on your birthday in either city. Adding your birth time gives the live counter a real starting instant; the years-months-days figure stays anchored to calendar dates, which is how ages are used on forms and in law.
Use the "age on date" field for paperwork that asks how old someone was on a specific date: school enrolment cut-offs, visa applications, insurance quotes, or pension and retirement rules that depend on your age on a given day.
Teachers, speech-language pathologists and psychologists can use the exact years-months-days output as a chronological age for assessment scoring; set "age on date" to the test date rather than today.
The milestone table doubles as a party planner: put the 10,000-day date, the billionth second, or a half-birthday in your calendar — they land on ordinary weekdays no one else is celebrating.
The equivalences in the fun-facts panel are estimates built on published averages: a resting heart rate of 70 beats per minute sits in the 60–100 range the American Heart Association describes for adults, resting breathing of about 16 breaths per minute matches the 12–20 range clinicians use, and the one-third-of-life sleep figure follows from the 7–9 hours per night recommended for adults. Planetary ages divide your age in Earth days by each planet’s orbital period from NASA’s planetary fact sheet — 88 days for Mercury up to 60,190 for Neptune.
Leap-day birthdays are a real legal question, not a novelty. About 1 person in 1,461 is born on 29 February and, in common years, jurisdictions split between 28 February and 1 March: the United Kingdom’s rule lands on 1 March, New Zealand’s on 28 February, Taiwan treats 28 February as the anniversary, and United States practice varies because no federal rule exists. If a contract, licence or benefit hinges on a leap-day birthday, check the rule that applies where you live.
Germany has the tidiest legal answer to "when exactly do I get older": under the Bürgerliches Gesetzbuch you complete a year of life at the start of your birthday — midnight — not at the hour you were born. Most countries behave the same way in practice, which is why the exact-age result is anchored to calendar dates and the birth-time option only refines the elapsed-time counters.
What this age calculator shows that others don’t
Cultural age systems computed, not just described: international age, traditional Korean age, Chinese xusui with real Lunar New Year boundaries, and calendar-year age side by side.
Milestone dates you can actually plan around: 10,000 days, 1,000 weeks, 500 months, one billion seconds and your next half-birthday, each with its calendar date.
Leap-day birthdays around the world
- United Kingdom: in common years, leap-day babies legally age on 1 March.
- New Zealand: the official birthday falls on 28 February when there is no 29th.
- Taiwan: the anniversary is commonly treated as 28 February in non-leap years.
- United States: no general rule — it depends on whether the day of birth is included or excluded in the count, so practice varies by jurisdiction.
- Germany: the civil code says a year of life completes at midnight at the start of the birthday, whatever the hour of birth.
Age systems still in use around the world
- South Korea unified on international age for legal purposes on 28 June 2023, making most people one to two years "younger" overnight.
- Calendar-year age (current year minus birth year) still governs Korean school entry, conscription and the drinking age — everyone born in the same year moves together on 1 January.
- Chinese nominal age (xusui) starts at 1 at birth and adds a year at each Lunar New Year; it survives in ritual use and in the traditional baby-gender chart.
- Japan abolished traditional counting (kazoedoshi) by law in 1902 and pushed everyday adoption of Western counting in 1950; the old system persists only in ceremonies.
Milestones worth putting in your calendar
10,000 days old arrives around age 27 years 4 months — a once-in-a-lifetime round number most people miss by a decade.
One billion seconds lands about 31 years and 8.5 months after birth; with a birth time entered, this page pins it to the exact second.
A half-birthday is exactly six months after the day itself — useful for December babies who want a summer party, and computed here with correct month-end handling.
FAQ
How is my exact age calculated?
The calculator counts complete years up to your most recent birthday, then complete months up to the same day of the month, then the days left over. Months are counted on the calendar, not averaged, so the answer matches how ages are counted legally and in everyday life.
How old am I if I was born in 1990?
Subtract 1990 from the current year, then subtract one more if your birthday has not happened yet this year. Someone born in 1990 turns the full difference on their birthday. Enter your full birth date above to get the exact answer in years, months and days.
How many days have I been alive?
Enter your date of birth and the total-days figure appears in the results, together with the same span expressed in weeks, months, hours, minutes and live-ticking seconds. As a rule of thumb, each year of age is roughly 365.25 days.
How old am I if I am 10,000 days old?
10,000 days is about 27 years and 4.5 months. The milestone table below the calculator shows the exact date you turned — or will turn — 10,000, 20,000 and 30,000 days old.
What happens if I was born on 29 February?
You still age one year per year, but countries disagree about the legal date: in the United Kingdom leap-day babies come of age on 1 March in common years, while New Zealand and Taiwan treat 28 February as the birthday. This calculator counts 1 March as the next birthday in common years and flags your date as a leap-day birth.
What year was I born if I am 21?
Subtract 21 from the current year if your birthday has already passed this year; subtract 22 if it has not happened yet. Use the "age on date" field together with a birth-year guess to check any combination.
What is my Korean age, and did it really change in 2023?
Traditional Korean counting starts life at age 1 and adds a year every 1 January, so it runs one to two years ahead of international age. Since 28 June 2023 South Korea uses international age for all legal and administrative purposes, but calendar-year age still decides school entry, conscription and the drinking age, and the traditional count survives in conversation. The cultural-age panel shows all of these at once.
Why does my Chinese zodiac sign depend on more than my birth year?
The zodiac year begins at Lunar New Year, which falls anywhere between 21 January and 20 February. Someone born on 1 February 2008 belongs to the Pig, not the Rat, because the Year of the Rat only began on 7 February 2008. Calculators that map calendar years straight to animals get roughly one in twelve people wrong; this one checks the actual New Year dates.
When will I be — or when was I — one billion seconds old?
One billion seconds is about 31 years and 8.5 months, so most people cross it in their early thirties. The milestone table shows your exact date; add your time of birth and the moment is computed to the second.
What is a chronological age and how is it written?
Chronological age is simply exact age — years, months and days between birth and a reference date. In education and clinical assessment it is often written as Y;M (for example 7;4) and computed to the test date, not to today. Set the "age on date" field to the assessment date and read the years and months from the exact-age result.
Why do different age calculators give different totals in months or days?
Three reasons: some average months to 30.44 days instead of counting the calendar; some include the end date as an extra day; and some clamp month-ends differently for people born on the 29th, 30th or 31st. This page counts real calendar months, excludes the end date (standard for age), and explains its month-end rule rather than leaving it as a surprise.