Age Calculator
Calculate age by date of birth and an as-of date, including exact years-months-days, full age, Japanese counting age, zodiac, Japanese era, days lived, seconds lived, and the next birthday.
Birth date and the day to calculate age
Example: how old is someone born on February 29, 2000 as of Mon, May 18, 2026? Choose the birth date and the as-of date to calculate it.
Enter a birth date to see the result.
Age Result
- Exact age
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- Counting age
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- Zodiac
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- Birth date in Japanese era
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- Birth date in Gregorian calendar
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- Birth weekday
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- As-of weekday
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- Days lived
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- Seconds lived
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- Next birthday
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Find birth dates from age
Find the birth date of someone aged 30 as of Mon, May 18, 2026. Add birth month and day to resolve it to one date.
If you know the birth month and day, add them to resolve the range to one birth date. Leave them blank to keep the range.
Enter an age to see the matching birth-date range.
- Date range
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- Weekday
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- Birth year guide
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- Japanese era range
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- Sexagenary zodiac
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- Western zodiac sign
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Age chart for 2026
The age chart keeps common milestone ages on the same page so you can cross-check the calculator result quickly.
| Full age | Birth year | Japanese era |
|---|---|---|
| 0 | 2026 | Reiwa 8 |
| 1 | 2025 | Reiwa 7 |
| 6 | 2020 | Reiwa 2 |
| 12 | 2014 | Heisei 26 |
| 15 | 2011 | Heisei 23 |
| 18 | 2008 | Heisei 20 |
| 20 | 2006 | Heisei 18 |
| 30 | 1996 | Heisei 8 |
| 40 | 1986 | Showa 61 |
| 50 | 1976 | Showa 51 |
| 60 | 1966 | Showa 41 |
| 65 | 1961 | Showa 36 |
| 70 | 1956 | Showa 31 |
| 75 | 1951 | Showa 26 |
| 80 | 1946 | Showa 21 |
Age only makes sense with an as-of date.
An age calculator is only reliable when it makes the reference date explicit. Forms, eligibility rules, school records, event policies, and profile pages may need age today, age on an application date, or age on a future deadline. This page separates the birth date from the reference date and shows full age, exact years-months-days, Japanese counting age, zodiac, Japanese era notation, days lived, and the next birthday in one place.
Finding a birth date from age
When you start from age alone, the answer is a range rather than a single date. Someone aged 18 on a reference date may have already had their birthday this year, or may still be waiting for it. The reverse calculator shows the matching birth-date range and birth-year guide for that reference date. If you also know the birth month and day, it resolves the range to one date and shows Japanese era, sexagenary zodiac, and Western zodiac sign.
Full age and legal context
Full age increases on a birthday. Japanese legal and administrative contexts often refer to the Act on Age Calculation and general civil-law period calculation concepts, so the exact rule used by a specific program or notice still matters. The calculator presents the result by calendar date and makes it easy to compare different reference dates before you write an eligibility statement.
Counting age, zodiac, and Japanese era
Counting age starts at one in the birth year and increases at New Year. It is not the primary method for most modern age limits, but it still appears in cultural contexts such as traditional celebrations. Japanese era notation is also useful for Japanese forms and records. Zodiac is shown by Gregorian birth year, not by a lunar calendar or Setsubun boundary.
Leap-day birthdays
February 29 birthdays need careful date validation because invalid dates can otherwise roll into another day in browser APIs. This tool validates real calendar dates before calculating. Try February 28, March 1, and February 29 in leap years as reference dates to see how full age and next-birthday countdowns change.
Using this with spreadsheets
Excel and Google Sheets are useful for large lists, but date formatting, text cells, and time zones can change the result. Use this page to verify the rule and wording first, then translate that rule into spreadsheet formulas for batch processing.