An age calculator tells you exactly how old you are — not just in years, but in months, days, hours, minutes, and seconds. The age calculator above takes your date of birth (and optionally any target date) and instantly returns your chronological age, your zodiac sign with its element and ruling planet, the weekday you were born, and how many days remain until your next birthday. Every calculation runs entirely inside your browser — nothing is uploaded, logged, or stored anywhere.
How to use the age calculator
Using the age calculator takes three seconds and no signup:
- Click the Date of birth field and pick the day you were born.
- Leave the “As of” field set to today, or pick any other date to find out how old you were on a past day — or how old you will be on a future one.
- Read your result. The big headline shows your age in years, months, and days. The grid below breaks the same span down into total months, weeks, days, hours, minutes, and seconds. Your zodiac panel and birthday weekday fill in automatically.
You can also press Download card to save a 1080 × 1350 PNG with your zodiac art, age headline, and constellation — sized for Instagram or any social feed.
How age is calculated
Your chronological age is the count of whole years that have passed since your birth, plus any leftover months and days. The formula sounds simple, but real birth dates introduce subtle traps: leap years, end-of-month rollovers, and the difference between “already had this year’s birthday” and “still waiting for it.”
Here is the exact algorithm the age calculator uses to compute your age from your date of birth:
- Subtract the birth year from the target year.
- Compare months. If your birth month falls later in the year than the target month, you haven’t reached this year’s birthday yet — subtract one from the year count.
- Compare days. If your birth day is later in the month than the target day, you haven’t reached this month’s birthday-anniversary yet — subtract one from the month count.
- The leftover days come from the calendar length of the previous month, so 28-, 29-, 30-, and 31-day months are all handled automatically.
Worked example
Born 15 June 1990, age calculated on 11 May 2026:
- Year diff: 2026 − 1990 = 36
- June (birth month) is later in the year than May (target month), so the 2026 birthday hasn’t happened yet. Age in years = 35.
- Counting from the previous birthday (15 June 2025) to 11 May 2026 gives 10 months + 26 days (April has 30 days, so the borrowed days are 30 − 4).
- Result: 35 years, 10 months, 26 days.
Your age in different units
Below the headline number, the stat grid converts your exact age into six different units. Each one is computed from the actual millisecond span between your birthday and the target date, so the totals stay accurate even across leap years.
Age in years and months
Total months equals (years × 12) + leftover months. Useful for legal forms or medical records that ask for an infant’s or toddler’s age in months. A 35-year-old who is 10 months past their last birthday has been alive for 430 months.
Age in weeks and days
Total days counts every calendar day you have lived — leap days included. Total weeks is days ÷ 7. This is the number people search for when they ask “how many days have I been alive”: at 35 years, 10 months, 26 days you have been alive roughly 13,114 days or 1,873 weeks.
Age in hours, minutes, and seconds
For curiosity (and for kids who like very large numbers): a 35-year-old has been alive for around 314,000 hours, 18.9 million minutes, or 1.13 billion seconds. The exact figure depends on your time of birth — which the age calculator assumes is midnight, since most public birth records only store the date.
Zodiac signs and their dates
The age calculator also identifies your Western tropical zodiac sign from your date of birth and shows it as a full-width panel with the sign’s glyph, name, element, ruling planet, and constellation art. The four classical elements — fire, earth, air, and water — each rule three signs:
| Sign | Glyph | Dates | Element | Ruling planet |
|---|---|---|---|---|
| Capricorn | ♑ | Dec 22 – Jan 19 | Earth | Saturn |
| Aquarius | ♒ | Jan 20 – Feb 18 | Air | Uranus |
| Pisces | ♓ | Feb 19 – Mar 20 | Water | Neptune |
| Aries | ♈ | Mar 21 – Apr 19 | Fire | Mars |
| Taurus | ♉ | Apr 20 – May 20 | Earth | Venus |
| Gemini | ♊ | May 21 – Jun 20 | Air | Mercury |
| Cancer | ♋ | Jun 21 – Jul 22 | Water | Moon |
| Leo | ♌ | Jul 23 – Aug 22 | Fire | Sun |
| Virgo | ♍ | Aug 23 – Sep 22 | Earth | Mercury |
| Libra | ♎ | Sep 23 – Oct 22 | Air | Venus |
| Scorpio | ♏ | Oct 23 – Nov 21 | Water | Pluto |
| Sagittarius | ♐ | Nov 22 – Dec 21 | Fire | Jupiter |
The constellation rendered behind your sign in the tool is not generic art — it is an approximation of the actual stars that form each zodiac, with dots and connecting lines positioned to match the recognisable shape.
Special cases
Leap year birthdays (29 February)
If you were born on 29 February you only get a “true” birthday every four years — and not even every fourth, because century years not divisible by 400 skip the leap day. The age calculator handles this the way most countries handle it legally: in non-leap years, your “next birthday” countdown lands on 28 February. In leap years, it lands on 29 February. Your chronological age still ticks over each calendar year — you don’t have to wait for a leap day to officially turn the next number.
Calculating age at a past or future date
The “As of” date defaults to today, but you can set it to any date — past or future. Two common uses: working out how old someone was on a specific historical date (a public figure’s age at a key moment, a relative’s age in an old family photo), or how old you will be on a future date (graduation, wedding, retirement, the day your child turns 18). Pick a target date and the age calculator updates the numbers instantly.
International age vs Korean age
This age calculator uses international age — the chronological count used in most countries. Korean traditional age, by contrast, counts you as 1 at birth and adds a year on every January 1, so it runs 1–2 years higher. South Korea officially switched to international age for legal and administrative purposes in June 2023, but the traditional system still surfaces in casual conversation. If you need your Korean age, add 1 to the calculator’s result if you have not yet had this year’s birthday, otherwise add either 1 or 2 depending on the source you are converting for.
What people use an age calculator for
The headline use case is also the most common one: filling in a form that asks for your exact age — usually in years, sometimes in years and months, occasionally in days for medical or veterinary records. But the age calculator is also useful for:
- Future planning — how old you will be at retirement, on a future graduation date, or on any other chosen day.
- Historical curiosity — how old a public figure was when they did something notable, or how old a relative was when a family photo was taken.
- Age verification for legal documents — drivers’ licenses, voting eligibility, retirement benefits, alcohol and tobacco restrictions all hinge on exact chronological age, and the days and months remainder matters around birthdays.
- Anniversary calculations — how many years, months, and days you have been married, employed, or living somewhere.
- Birthday countdowns — exactly how many days until your next birthday and what weekday it falls on.
- Conversation starters — finding the weekday you were born on, or your zodiac sign, which the age calculator returns alongside the age figures.
- The “billion seconds” milestone — at roughly 31.7 years old, you cross the one-billion-seconds mark. Some families mark it.
Privacy and how the age calculator works
Every calculation in this age calculator runs inside your browser using plain JavaScript. Nothing you type — your date of birth, the target date, anything — is sent to a server, logged in any database, or saved to disk. Closing the tab erases everything. There are no cookies, no tracking pixels, no third-party APIs, and no signup of any kind.
The downloadable PNG card is also generated locally: the canvas element in your browser renders the image and saves it directly to your device. The card never passes through this site’s servers either. That means you can use this age calculator confidently with sensitive data — there is nothing here for us to leak, lose, or hand over.