日付の差を計算
2つの日付の間隔を計算します。
計算ツール
年齢計算
年・月・日単位で年齢を計算します。
入力内容
UtilBrix が提供結果
Your age
26 years, 9 months, 18 days
- Total months
- 321
- Total weeks
- 1,398
- Total days
- 9,788
- Total hours
- 234,912
- Total minutes
- 14,094,720
- Next birthday
- 2027年1月1日
- Days until birthday
- 74
- Day of birth
- 土曜日
For February 29 birthdays, February 28 is used in non-leap years. Calendar totals exclude time-of-day.
詳しい方法と使用例は英語で提供しています。
Step-by-step instructions (English)
- Enter the date of birth using the date picker.
- Choose today or the specific date on which you need the age.
- Calculate and read calendar years, months, and days separately from the total elapsed days.
計算式と方法
Count complete calendar months between the birth and target dates, then count the remaining days. Years contain 12 calendar months. February 29 anniversaries fall on February 28 in a non-leap year. Total days are measured between UTC calendar dates, avoiding daylight-saving effects.
使用例
A person born on 1 January 2000 is 25 years, 6 months, and 14 days old on 15 July 2025.
When this tool is useful
Check an age on a school reference date, prepare a birthday milestone, or compare an age today with an age on a future date. Use the target-date field rather than manually adjusting the year, especially when the birthday has not yet occurred.
Common mistakes and limitations
- A year is not always 365 days, and a calendar month is not always 30 days. Avoid converting the total days back to years with a fixed divisor.
- The February 29 convention is a calculation choice; an organization may apply a different rule for legal eligibility.
Practical questions about this tool (English)
Why does subtracting the birth year give a different answer?
Year subtraction ignores whether the birthday has happened on the target date. Someone born in December has not completed another year in January, even though the calendar year has changed.
Does this calculate age down to the time of birth?
No. It uses calendar dates, not birth times or time zones. Use Time Duration Calculator if you need a duration between specified times.