Guides JP

Age Calculator Tool

Enter your birthday to see your age, days lived, Chinese zodiac, zodiac sign, birthstone, graduation years, and milestone celebrations in a "Life Dashboard" view.

Last updated: 2026/10/16 Calculator Feedback & bug reports
Birthday Input
For Yakudoshi calculation

How to Use

1

Enter Your Birthday

Type "1985/3/15" in the Quick Input field, or select year, month, and day using the Western Year or Japanese Era mode.

2

View Your Life Dashboard

As you type, your age, days lived, half birthday, school grade in Japan, zodiac, birthstone, graduation years, milestone celebrations and legal age milestones are instantly displayed in card format.

3

Copy Results

Choose a format (Resume, Full Info, or Age Only) and click "Copy Result" to copy to clipboard. Spreadsheet formulas have their own copy buttons.

About Age Calculator

A web tool that displays your full age, Kazoe age, days lived, Chinese zodiac, unlucky years (Yakudoshi), zodiac sign, birthstone, education timeline, milestone celebrations, school grade in Japan and legal age milestones in a single "Life Dashboard" view. Supports Japanese era input. All processing happens in your browser - no data is sent to any server.

This tool now also shows your exact age in years/months/days, weeks lived, total hours lived, the countdown to your next birthday, and the day of the week you were born. To check just the weekday of any date, use the Day of the Week Calculator; to count the number of days between two dates, try the Date Calculator; and to look up your Chinese zodiac and star sign together, see the Eto & Zodiac Checker.

Related: Era Converter

Features

  • Life DashboardAll age-related information displayed in card format on a single page. No need to visit multiple pages.
  • Japanese Era Quick InputType "Showa 60", "S60.3.15" etc. in free text and it auto-detects the format.
  • Yakudoshi Detection (Gender-Aware)Shows Mae-yaku, Hon-yaku, Ato-yaku, and Tai-yaku. Different unlucky years for male and female.
  • Privacy ProtectedAll processing happens in your browser. Your birthday data is never sent to any server.
  • School Grade in Japan & Half BirthdaySee which grade or nursery class a child is in under Japan's April-to-March school year (early-born aware), plus a countdown to the next half birthday.
  • Age Milestones & Spreadsheet FormulasDates you reach 18, 20, 60, 65, 70 and 75 under Japanese rules, 10,000-day milestones, and ready-to-copy DATEDIF formulas for Excel and Google Sheets.

Use Cases

  • Verify age and graduation years for resumes
  • Calculate age for official documents
  • Find which grade a child would be in at a Japanese school, or their next half birthday
  • Check when you reach 60, 65 or 75 under Japanese pension and medical rules
  • Check milestone celebrations and Yakudoshi (unlucky years) for family
  • Look up Chinese zodiac, zodiac sign, and birthstone
  • Calculate ages automatically in Excel or Google Sheets

FAQ

What is the difference between full age and Kazoe age?
Full age counts from 0 at birth and adds 1 on each birthday. Kazoe age counts from 1 at birth and adds 1 every New Year's Day (January 1). Modern Japanese law uses full age, but Yakudoshi and milestone celebrations sometimes use Kazoe age.
When are the Yakudoshi years for men?
Men's Yakudoshi are at Kazoe ages 25, 42, and 61. Each has a before-year (Mae-yaku) and after-year (Ato-yaku). Age 42 is called "Tai-yaku" (major unlucky year). This tool auto-detects when you enter birthday and gender.
When are the Yakudoshi years for women?
Women's Yakudoshi are at Kazoe ages 19, 33, 37, and 61. Age 33 is considered "Tai-yaku" (major unlucky year). Select gender to see the correct unlucky years.
How is the Chinese zodiac determined?
The Chinese zodiac cycles through 12 animals based on the remainder when dividing the Western year by 12: Rat, Ox, Tiger, Rabbit, Dragon, Snake, Horse, Sheep, Monkey, Rooster, Dog, and Boar.
How are graduation years affected by early birth dates?
In Japan, those born January 1 to April 1 are placed in the grade above those born April 2 onward of the same year. This tool auto-detects early-born status from the birthday.
When are milestone celebration years?
Major milestones: Kanreki (60), Koki (70), Kiju (77), Sanju (80), Beiju (88), Sotsu-ju (90), Hakuju (99), Hyakuju (100), Chaju (108), Koju (111). This tool shows all milestones with both Japanese era and Western year.
What Japanese era input formats are supported?
Formats like "Showa 60/3/15", "S60.3.15", "H1.1.8", "Reiwa 8", "R8" are auto-recognized. Just type or paste in the Quick Input field.
Can I change the reference date?
Yes, the default is today but you can change it to any date. Useful for checking "how old on a specific date".
Is my data saved?
No, all processing is done entirely in your browser. No data is sent to or stored on any server.
What are the birthstones by month?
January: Garnet, February: Amethyst, March: Aquamarine, April: Diamond, May: Emerald, June: Pearl, July: Ruby, August: Peridot, September: Sapphire, October: Opal, November: Topaz, December: Tanzanite.
Can it show my exact age in years, months, and days?
Yes. When you enter a full birthday (year, month, and day), the "Lifetime Stats" card shows your exact age as "X years, Y months, Z days", along with the number of weeks and total hours you have lived. Change the reference date to check your detailed age as of any past or future date.
How many days until my next birthday, and what day of the week was I born?
The "Detailed Info" card shows the number of days remaining until your next birthday plus that birthday's date and weekday. The "Basic Info" card shows the day of the week you were born (Sunday to Saturday). For February 29 birthdays, the next birthday is calculated as March 1 in non-leap years.
Can it tell which grade a child would be in at a Japanese school?
Yes. Enter a birthday to see the grade or nursery class for the school year that contains the reference date (today by default): the age 0-2 nursery classes, the three kindergarten years, elementary grades 1-6, junior high and high school years 1-3, and university years 1-4, then an estimate of working years. Japanese school years run from April to March. Children born April 2 to the following April 1 share a grade, so those born January 1 to April 1 ("early-born") are one grade above children born later in the same calendar year. Nursery classes go by age on April 1. The result assumes no repeated or skipped years.
When is my half birthday?
Your half birthday is the same day six months after your birthday, and the tool counts down to the next one. If that month has no matching day, the last day of the month is used: an August 31 birthday gives February 28 (29 in leap years), and a March 31 birthday gives September 30. A February 29 birthday gives August 29.
Why is the Japanese "age attainment date" the day before the birthday?
Under Japan's Act on Calculation of Age and Article 143 of the Civil Code, you legally reach a new age at the end of the day before your birthday. Pensions use that date: someone born on April 1 reaches 65 on March 31 and is paid from April. The late-stage elderly medical care system, however, starts on the 75th birthday itself. The "Age Milestones in Japan" card lists the dates for 18, 20, 60, 65, 70 and 75 together with the rule each system uses.
What Excel or Google Sheets formula calculates age?
With the birthday in cell A1, use =DATEDIF(A1,TODAY(),"Y") for age in years, =DATEDIF(A1,TODAY(),"Y")&" years "&DATEDIF(A1,TODAY(),"YM")&" months" for years and months, and =DATEDIF(A1,TODAY(),"D") for days lived. DATEDIF is not listed in Excel's function suggestions but works when typed in full. The "Excel & Google Sheets Formulas" card can also copy versions with your birthday built in.

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