Age Calculator by Date of Birth

This Age Calculator by Date of Birth shows more than a basic “you are X years old” answer. It gives your exact age in years, months, and days, plus useful extra results like total days lived, full weeks lived, full months lived, day of the week you were born, next birthday date, birthday countdown, and Western zodiac sign.

Age Calculator by Date of Birth

Enter your date of birth to calculate your exact age in years, months, days, weeks, and more.

Use this age calculator to find your exact age from your date of birth. You can calculate your age as of today or choose any custom date.

This calculator uses calendar dates for exact age in years, months, and days. For February 29 birthdays, the next birthday countdown uses February 28 in non-leap years.

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What results does this age calculator show?

After you enter a date of birth, the calculator gives a detailed age summary. The main result shows your exact age in calendar years, months, and days. Under that, you will see several extra breakdowns that are useful for forms, planning, records, and personal milestones.

Exact age: Your age in years, months, and days.
Total days old: The total number of days between the birth date and the selected date.
Total weeks old: Your age converted into full weeks, with leftover days shown separately.
Total months old: The number of full calendar months completed.
Born on: The day of the week for the date of birth.
Western zodiac sign: The zodiac sign based on the month and day of birth.
Next birthday: The date of the next birthday after the selected date.
Birthday countdown: How many days are left until the next birthday.
Detailed breakdown: Approximate totals in months, weeks, days, hours, and minutes.

Calculate your age today or on another date

The tool can calculate age as of today or as of a custom date. The custom date option is useful when you need to know how old someone was in the past or how old someone will be in the future.

For example, you can use it to check age on a school cutoff date, event date, application deadline, birthday, travel date, medical record date, insurance date, or any other specific day.

Why exact age is not just birth year subtraction

Exact age depends on whether the birthday has already happened by the selected date. Someone born in December and someone born in January of the same year are not always the same age. This calculator compares the full birth date against the target date, including year, month, and day.

What “total months” means

The total months result shows full completed months. For example, if someone is 20 years, 4 months, and 10 days old, the calculator counts the 20 years and 4 completed months, but it does not round the extra 10 days into another month.

What “total weeks” means

The total weeks result shows full completed weeks plus the remaining days. This is useful when age in weeks matters, such as for baby age, pregnancy-related references, early childhood milestones, short-term planning, or countdowns.

What “total days, hours, and minutes” mean

The total days result is the exact number of calendar days between the birth date and the selected date. The hours and minutes results are approximate conversions from total days. They are useful for fun facts and quick estimates, but they do not account for the exact time of birth.

Birthday countdown and next birthday

The calculator shows the next birthday after the selected date and how many days are left until that birthday. If the selected date is the birthday, the result will say that the birthday is today.

Leap year birthdays

For people born on February 29, birthday handling can vary depending on the situation. This calculator uses February 28 as the birthday date in non-leap years for the birthday countdown. For official forms or legal rules, follow the policy of the organization asking for the age.