Age Calculator – How Old Am I?

To calculate your age, subtract your birth year from the current year, and subtract one more if your birthday hasn't come yet this year. Enter your date of birth above to get your exact age in years, months and days, plus total days, weeks and hours, your next birthday, star sign and Chinese zodiac.

How to use this calculator

1. Enter your date of birth.
2. Leave “Age on” as today, or change it to see how old you were, or will be, on another date.
3. Read your age in years, months and days.
4. Check the totals — months, weeks, days and hours — and the countdown to your next birthday.
5. Use the share button to send the result; the link keeps the dates you entered.

How it's calculated

• Years and months: the calculator counts whole calendar months from your birth date to the “age on” date. Whole years = months ÷ 12; the rest are months.
• Days: the days left after the last whole month. If your birth day doesn't exist in a month (the 31st, or 29 February), that month's anniversary falls on its last day.
• Totals: total days is the exact day count between the two dates; weeks is days ÷ 7 and hours is days × 24.
• Next birthday: your birth date plus your next age in years, with the same last-day-of-month rule.

This is the everyday “completed years” age used for most forms. It counts whole days, not the time of birth.

Worked examples (as of Friday, September 25, 2026)

Born 31 May 1993

Age on Friday, September 25, 2026: 33 years, 3 months and 25 days. That's 399 months, 1,738 weeks or 12,170 days in total. Born on a Monday, and in the Year of the Rooster.

Born 15 January 1987

On Friday, September 25, 2026 the age is 39 — exactly 39 years, 8 months and 10 days. Because 15 January falls before Lunar New Year, the Chinese zodiac sign is the Tiger, not the animal for 1987.

Born 29 February 2000

Age on Friday, September 25, 2026: 26 years, 6 months and 27 days. The next birthday is shown as Sunday, February 28, 2027, because this calculator uses 28 February in years without a 29th.

How to calculate age by hand

1. Subtract the birth year from this year. For someone born on 31 May 1993, 2026 − 1993 = 33.
2. If this year's birthday hasn't happened yet, subtract 1. That gives completed years.
3. Count whole months from the last birthday to today. If today's day of the month is smaller than the birth day, the current month isn't complete yet.
4. Count the remaining days from the last whole-month date to today.

Doing this by hand is where most errors creep in, because months have different lengths. The calculator does the same steps on the real calendar, so it handles 31st-of-the-month and leap-day birthdays consistently.

How old is someone born in [year]? Age chart 1940–2015

Take the current year minus the birth year, or one less if the birthday hasn't come yet this year. Someone born in 1993 is 33 after their 2026 birthday and 32 before it; born in 1978, 48 or 47; born in 1983, 43 or 42.

Date of birth for age 18, 21 and other ages today

Working backwards — for an age check, a form or a birthday-date question — this table gives the birth dates that make someone exactly that age today. As of Friday, September 25, 2026, a 21-year-old was born between September 26, 2004 and September 25, 2005.

Age in days: milestone birthdays

When do you turn 10,000 days old? For someone born on Monday, May 31, 1993:

Leap-year birthdays and legal age

If you were born on 29 February, your birthday only appears on the calendar in leap years. Most of the time this doesn't matter, but it can when a legal age starts on a set day. The rules differ:

• Scotland — in a common year you reach the age on 1 March (Age of Legal Capacity (Scotland) Act 1991, s.6).
• Hong Kong — also 1 March (Age of Majority (Related Provisions) Ordinance, Cap. 410, s.5).
• England & Wales — you attain an age at the start of the relevant anniversary of your birth date (Family Law Reform Act 1969, s.9), with no specific leap-day rule.

This calculator uses 28 February, the common everyday convention. If a legal right, benefit or deadline depends on your exact age, check the rule where you live — this page is not legal advice.

Common mistakes

• Subtracting years only. 2026 − 1993 = 33, but anyone born later in the year than today is still 32.
• Counting months as 30 days. Months are 28 to 31 days long, so “days” in an age depends on which months you cross. The calculator uses the real calendar.
• Chinese zodiac by year only. If you were born before Lunar New Year, your animal is the previous year's.
• Star-sign cusps. Sources differ by a day at the edges of signs, partly because the equinox and solstice dates shift slightly year to year.

Related: check eligibility by date of birth with the NDA age calculator, or count days, weeks and months between any two dates with the days from today calculator.

Frequently asked questions

Sources & method

• Age of Legal Capacity (Scotland) Act 1991, s.6 — 29 February birthdays
• Hong Kong Age of Majority (Related Provisions) Ordinance, Cap. 410 s.5
• Family Law Reform Act 1969, s.9 — time at which a person attains a particular age
• Hong Kong Observatory — Gregorian–Lunar calendar conversion tables
• Weber State University — astrological vs astronomical zodiac dates
• U.S. Naval Observatory — leap years

Results are estimates for general information. Found an error? It helps everyone — see our methodology.