Age Calculator
Use this free online Age Calculator to calculate your exact age in years, months and days. You can also calculate your total days, total weeks, approximate total months and your next birthday.
Calculate Your Exact Age
What Is an Age Calculator?
An age calculator is an online tool that calculates the amount of time between a person's date of birth and a selected date. Unlike a simple subtraction of birth years, an exact age calculation considers the actual calendar months and days between the two dates.
Smart Unit Calc's age calculator can calculate chronological age in years, months and days. It can also show the total number of completed days and weeks between the dates.
How to Use the Age Calculator
- Enter your date of birth.
- Enter the date on which you want to calculate your age.
- Click the Calculate Age button.
- View your exact age in years, months and days.
- Review your total days, total weeks and next birthday.
Age Calculation Formula
Age is calculated by finding the calendar difference between the date of birth and the calculation date.
The calculation is performed using calendar years, months and days rather than assuming that every year has the same number of days or that every month has the same number of days.
Age Calculation Example
Date of birth: January 15, 1995
Calculation date: September 8, 2026
Age: 31 years, 7 months and 24 days
The result represents the completed calendar years, months and days between the two dates.
Age in Years, Months and Days
Expressing age in years, months and days is useful when an exact chronological age is required. For example, instead of saying someone is approximately 31.65 years old, an age calculator can report the calendar-based result as 31 years, 7 months and 24 days.
Age in Days
The total days result represents the calendar-day difference between the date of birth and the selected calculation date. Leap years are included automatically because February can contain 29 days.
Total days can be useful for date calculations, milestone tracking, project planning and determining how much time has passed between two dates.
Age in Weeks
One week contains seven days. Therefore, the total number of weeks can be calculated by dividing the total number of completed days by seven.
The weeks value may contain a decimal because a person's age does not necessarily contain a whole number of weeks.
Age in Months
Calendar months do not all contain the same number of days. For this reason, an exact age in calendar months should be expressed using years, months and days.
For an approximate total-month calculation, this calculator uses the average Gregorian year length of approximately 365.2425 days, equivalent to approximately 30.436875 days per month.
Age and Leap Years
A leap year normally contains 366 days instead of 365. Leap years are important when calculating the exact number of days between two dates.
The Gregorian calendar generally treats a year as a leap year when it is divisible by 4, except for century years that are not divisible by 400. For example, 2024 was a leap year, while 2100 will not be a leap year.
How Old Am I?
To find out how old you are, enter your date of birth and use today's date as the calculation date. The calculator will determine your age in completed years, months and days.
You can also choose a different date to find out how old you were on a past date or how old you will be on a future date.
Age Calculator for Future Dates
An age calculator can also be used to calculate your age on a future date. For example, you can enter a future birthday, anniversary or another important date to determine your chronological age at that time.
The selected calculation date must be the same as or later than the date of birth.
Age Difference Between Two Dates
The same calculation method can be used to determine the age difference between two dates. Enter the earlier date as the date of birth and the later date as the calculation date.
This can be useful for comparing ages, calculating eligibility dates, checking time intervals and determining the duration between important dates.
What Is Chronological Age?
Chronological age is the amount of time that has passed since a person's date of birth. It is normally expressed in completed years and is based on calendar dates.
Chronological age is different from biological age, developmental age or other concepts that may use health, physical or developmental characteristics.
Common Uses of an Age Calculator
- Calculating current age from a date of birth
- Finding exact age in years, months and days
- Calculating age on a specific past or future date
- Finding the number of days between two dates
- Calculating approximate age in weeks or months
- Checking birthdays and upcoming age milestones
- Comparing the difference between two dates
- Planning personal and family milestones
- Calculating date-based eligibility periods
Age Calculation for February 29 Birthdays
People born on February 29 have a leap-day birthday. Because February 29 does not occur in every year, different organizations and legal systems can use different rules for determining the birthday in a non-leap year.
This calculator keeps the original February 29 birth date for its calendar calculation rather than automatically changing it to February 28 or March 1. If an official age or legal deadline is involved, use the rule applicable to your jurisdiction or organization.
Age Calculator Accuracy
The calculator uses calendar dates and the actual number of days in each month. This provides a more useful result than simply subtracting the birth year from the current year.
The total-day calculation uses calendar dates rather than assuming that every day contains exactly the same local elapsed time. This helps avoid daylight-saving-time effects when dates are compared.
Frequently Asked Questions
How does the age calculator work?
The age calculator compares your date of birth with a selected end date and calculates the difference in complete years, months and days.
How do I calculate my age from my date of birth?
Enter your date of birth, select the date on which you want to calculate your age, and click Calculate Age.
Can I calculate my exact age in years, months and days?
Yes. The calculator provides your age in completed years, months and days based on the two dates entered.
Can I calculate age between two dates?
Yes. Enter the first date as the date of birth and the second date as the calculation date to calculate the difference between the two dates.
How many days old am I?
The calculator estimates your total completed days by calculating the calendar-day difference between your date of birth and the selected calculation date.
Does the age calculator account for leap years?
Yes. The calculator uses the actual number of days in each calendar month, including February during leap years.
What is chronological age?
Chronological age is the amount of time that has passed from a person's date of birth to a specified date.
Can I calculate my age on a future date?
Yes. You can enter a future calculation date to determine how old you will be on that date.
How is age calculated for a February 29 birthday?
For a February 29 birthday, the exact birthday convention in non-leap years can vary. This calculator keeps February 29 as the original birth date for calendar calculations.
Is this age calculator free?
Yes. Smart Unit Calc provides this age calculator free to use online.