Age Calculator - Exact Years, Months & Days

How old are you, exactly? Not just the number you give at birthday parties, but your precise age down to the month and day.

Whether you need your exact age for an official form, want to know what day of the week you were born on, are curious about your zodiac sign, or just want a countdown to your next birthday, this age calculator gives you a complete breakdown instantly.

Enter your date of birth and the tool calculates your age in years, months, and days. It also shows your age expressed entirely in months, entirely in weeks, entirely in days, and entirely in hours for those who enjoy seeing just how many hours they have been alive. Additionally, the calculator identifies your day of birth, your Western zodiac sign, your Chinese zodiac animal, and how many days remain until your next birthday.

This tool is useful for more than curiosity. Many legal, medical, and administrative situations require an exact age calculation. School enrollment cutoff dates, age-restricted activities, retirement eligibility, insurance applications, and visa requirements all depend on precise age computation that accounts for varying month lengths and leap years.

How Age Is Calculated

Age calculation seems simple until you consider the edge cases. The standard method used worldwide counts the number of complete years, months, and days that have elapsed since a person’s date of birth.

The basic rule: You turn one year older on each birthday. Between birthdays, your age in completed years remains the same. A person born on March 15, 1990, is 35 years old from March 15, 2025, until March 14, 2026, at which point they turn 36.

Month counting. Months are counted from the birth date to the same date in each subsequent month. If you were born on January 31 and today is March 15, one complete month passed from January 31 to February 28 (or 29), and then 15 additional days in March. The tricky part is that months have different lengths (28, 29, 30, or 31 days), so "one month" is not a fixed number of days.

Leap year handling. People born on February 29 (leap day) have their birthday in a year that only occurs every four years. In common years, most legal systems consider their birthday to be March 1 for age calculation purposes, though some jurisdictions use February 28. This calculator handles leap year birthdays correctly, showing the person as having their birthday on February 29 in leap years and computing age accurately in non-leap years.

Age in Different Units

Beyond the standard years-months-days format, your age can be expressed in several other units.

Age in months. A 30-year-old has lived approximately 360 months, but the exact number depends on the specific months involved (since months range from 28 to 31 days). This calculator computes the exact month count based on your actual birth date.

Age in weeks. One year contains approximately 52.177 weeks, so a 25-year-old has lived roughly 1,304 weeks. Again, the exact count depends on the specific dates.

Age in days. Accounting for leap years, a 30-year-old has lived approximately 10,957 to 10,958 days, depending on how many leap years fell within that span. This calculator counts every day precisely.

Age in hours. Multiply your age in days by 24. A 25-year-old has been alive for approximately 219,000 hours. This number can be sobering or motivating, depending on your perspective.

Zodiac Signs by Birth Date

This calculator identifies your Western zodiac sign based on your birth date. The zodiac divides the year into twelve signs, each spanning roughly 30 days.

Western Zodiac Signs:

Aries: March 21 to April 19
Taurus: April 20 to May 20
Gemini: May 21 to June 20
Cancer: June 21 to July 22
Leo: July 23 to August 22
Virgo: August 23 to September 22
Libra: September 23 to October 22
Scorpio: October 23 to November 21
Sagittarius: November 22 to December 21
Capricorn: December 22 to January 19
Aquarius: January 20 to February 18
Pisces: February 19 to March 20

Note that these date ranges can vary by one day depending on the year and the source, because the astronomical events they are based on (the sun entering each constellation) do not fall on exactly the same date every year.

Chinese Zodiac

The Chinese zodiac follows a 12-year cycle, with each year associated with an animal. Unlike the Western zodiac, which is based on your birth month, the Chinese zodiac is based on your birth year. However, the Chinese New Year falls in January or February, so people born in those months need to check whether their birth date falls before or after the Chinese New Year of that year.

The 12 Chinese Zodiac Animals (in cycle order): Rat, Ox, Tiger, Rabbit, Dragon, Snake, Horse, Goat, Monkey, Rooster, Dog, Pig

Each animal is associated with personality traits in Chinese astrology. The cycle repeats every 12 years, so people born 12, 24, 36, or 48 years apart share the same zodiac animal.

Birthstone and Birth Flower by Month

Each birth month is traditionally associated with a gemstone and a flower.

Birthstones:

January: Garnet
February: Amethyst
March: Aquamarine
April: Diamond
May: Emerald
June: Pearl or Alexandrite
July: Ruby
August: Peridot
September: Sapphire
October: Opal or Tourmaline
November: Topaz or Citrine
December: Tanzanite, Zircon, or Turquoise

Age Requirements for Common Milestones

Exact age matters for many legal and practical milestones. Requirements vary by jurisdiction, but here are common US thresholds.

Legal milestones in the United States:

Eligible for a work permit: 14 to 16 (varies by state)
Eligible for a driver’s permit: 15 to 16 (varies by state)
Eligible for a full driver’s license: 16 to 18 (varies by state)
Eligible to vote: 18
Eligible to purchase tobacco: 21
Eligible to purchase alcohol: 21
Eligible to rent a car (standard): 25 (though many companies rent to 21+ with surcharges)
Eligible for Medicare: 65
Full Social Security retirement age: 66 to 67 (depending on birth year)

Age for school enrollment typically requires a child to turn 5 years old by a specific cutoff date (usually September 1 or December 1, depending on the state) to enter kindergarten for that school year.

How to Calculate Age Between Two Dates

Sometimes you need to calculate someone’s age not as of today but as of a specific past or future date. Common scenarios include determining age at the time of a historical event, calculating age on a future date for planning purposes, or figuring out how old you were when something significant happened.

This calculator lets you enter both a birth date and a target date. It then computes the exact age as of that target date using the same year-month-day method. This is useful for applications like insurance that need age as of a policy date, or school enrollment that needs age as of a cutoff date.

Fun Age Statistics

Here are some perspective-giving statistics about human lifespans, based on average life expectancy in developed countries of approximately 78 to 82 years.

In an average lifetime, a person:

Lives approximately 28,000 to 30,000 days
Sleeps for roughly 26 years (one-third of their life)
Spends about 13 years working
Eats approximately 80,000 meals
Takes about 650 million breaths
Has a heart that beats roughly 2.5 to 3 billion times

These numbers underscore just how much time we have and how we choose to allocate it. For calculations involving specific dates, such as the number of days between two events, try the Date Calculator.

Day of the Week Calculator

Ever wondered what day of the week you were born on? This calculator tells you. The day of the week for any date can be determined using Zeller’s congruence or similar algorithms that account for the Gregorian calendar’s rules about month lengths and leap years.

Fun fact: the probability of being born on any particular day of the week is not exactly equal. Studies of birth data show that slightly more births occur on Tuesdays and Wednesdays (due to scheduled C-sections and induced labors) and fewer on Saturdays and Sundays (when fewer elective procedures are scheduled).

Frequently Asked Questions

How do I calculate my exact age?

Enter your date of birth into this calculator and it computes your age in years, months, and days automatically. It accounts for varying month lengths and leap years to give you a precise result.

What day of the week was I born on?

Enter your birth date and the calculator will show you the day of the week. The calculation uses the Gregorian calendar rules to determine the correct day for any date.

How does the calculator handle leap year birthdays (February 29)?

People born on February 29 have their birthday computed correctly in leap years. In non-leap years, the calculator treats their age as advancing on March 1, which aligns with how most legal systems handle leap day birthdays.

What is my zodiac sign?

Your Western zodiac sign is determined by your birth date. The twelve signs span approximately one month each, from Aries (March 21 – April 19) through Pisces (February 19 – March 20). Enter your birth date to see your sign.

How many days old am I?

The calculator converts your age to total days, accounting for leap years. As a rough estimate, multiply your age in years by 365.25 (the average year length including leap years). For an exact count, use this tool.

What is the Chinese zodiac and how does it work?

The Chinese zodiac is a 12-year cycle where each year is associated with an animal (Rat, Ox, Tiger, Rabbit, Dragon, Snake, Horse, Goat, Monkey, Rooster, Dog, Pig). Your sign is based on your birth year, but if you were born in January or February, check whether your date falls before or after the Chinese New Year.

Can I calculate age as of a specific date in the past or future?

Yes. This calculator lets you enter both a birth date and a target date. It computes the exact age as of that target date, which is useful for insurance applications, school enrollment cutoffs, and historical age calculations.

Zodiac dates and calendar calculations based on Gregorian calendar standards. Data accurate as of: March 2026