Age Calculation
Age Calculator
When you enter a date of birth and a reference date, the system calculates the age in years, months, and days, and you can also check the number of days elapsed and the number of days until the next birthday.
Calculation Results
Please enter your date of birth.
What is the Age Calculator?
The Age Calculator is a free tool that accurately calculates a person’s age in full years based on their date of birth and any specified reference date. You can check not only your current age as of today, but also how old you will be on a specific date in the past or future. It can be used for filling out age fields on resumes or application forms, verifying age requirements for certifications, and managing family anniversaries.
The calculation results display the standard age in "years, months, and days," as well as the total number of days since birth, the approximate total number of weeks, the number of full months that have passed, the next birthday, and the number of days until that date. Date calculations are performed within the browser; the entered date of birth is not sent to the server.
Calculations take into account the number of days in each month and leap years. For individuals born on February 29, in years when that date does not exist, calculations are based on February 28. Since the treatment of the date a person reaches a certain age may vary depending on laws and regulations, please verify the provisions of each relevant system when conducting official procedures.
Items displayed
- Display the full age as "○ years, ○ months, ○ days."
- Displays the total number of days that have elapsed from the date of birth to the reference date.
- Displays the approximate number of weeks elapsed, calculated by dividing the total number of days by 7.
- Displays the number of full moons remaining until the next monthly birthday.
- Displays the next birthday after the reference date and the number of days until then.
How to Use
- Enter your birthday in the "Date of Birth" field.
- Change the "Reference Date" as needed. The default value is today's date.
- Click "Calculate Age."
- Check the results for age in years, number of days elapsed, next birthday, and so on.
- If you want to use the results elsewhere, click "Copy Results."
Precautions for Use
- This tool calculates the standard full age based on the difference in calendar dates.
- Japanese law has its own specific provisions regarding the exact time of reaching a certain age. Please check with the relevant authorities regarding determinations related to official qualifications, contracts, and benefits.
- The total number of weeks is calculated by dividing the total number of days by 7 and is displayed to the second decimal place.
- By specifying a future reference date, you can calculate the age as of that date.
Frequently Asked Questions
Can you calculate my current age?
Yes. Please enter the date of birth and use the default reference date for the calculation.
Can you also calculate ages as of past or future dates?
Yes. If you change the reference date to any date, you can calculate the full age as of that date.
What is "age in full years"?
This is the standard method of counting age, where the day of birth is considered age 0, and one year is added for each birthday.
Does it support the Japanese age-counting system?
No. This tool calculates age based on the international standard. The traditional Japanese counting method treats a person as 1 year old at birth and adds one year with each New Year.
How is the date calculated for someone born on February 29?
In common years without a birthday, calculations are based on February 28.
Do you know how many days have passed since you were born?
Yes. It displays the total number of days elapsed up to the reference date.
Can you also tell me how many days are left until my next birthday?
Yes. It displays the date of the next birthday and the number of days since the reference date.
Can this be used to verify the age listed on a resume?
This can be used for general age verification. If the submitting party specifies a reference date, please set that date as the reference date.
Will the date of birth I entered be saved?
No. The calculation is performed within the browser, and the date of birth is not sent to the server.
Is it free to use?
Yes. You can use it for free without registration.