Age Calculator
Calculate precise age and total days between two dates
Age Calculator — what it does
Enter a birth date and a target date and this tool reports the exact age in years, months and days, plus the total number of days between the two dates. It walks the calendar month by month rather than dividing by 365, so leap years, 28-day Februarys and 31-day months are all handled correctly.
When this tool helps
- HR and school admissions work, where eligibility is defined as an age on a specific cut-off date rather than today.
- Filling in forms that ask for age in completed years and months, such as visa, insurance or medical paperwork.
- Counting the exact days an asset, contract or probation period has been running for a report.
How to use it
- Pick the birth date in the first field.
- Set the second date — it defaults to today, but any date works.
- Press Calculate.
- Read years, months, days and the total-days figure in the results.
Accuracy, limits, and good practice
- Age in completed years drops the remaining months, which is why someone one day short of a birthday still shows the lower year.
- The month-and-day breakdown depends on the order of the dates; a target date earlier than the birth date has no meaningful age.
- Total days counts calendar days, including weekends and holidays, and is not adjusted for time zones or clock time.
Frequently asked questions
Does it handle leap years?
Yes. February 29 is counted as a real date, and someone born on it is treated as ageing on March 1 in non-leap years, which is the common civil convention.
Can I calculate age at a past date?
Yes. Set the second date to any date in the past to get the age as it stood then — useful for backdated eligibility checks.
Why does the total-days number look larger than expected?
Total days is the full calendar count between the two dates. Twenty years is over 7,300 days once the five leap days are included.
Related tools on this site
- Compound Interest Calculator — Estimate future value with compounding and regular contributions
- Loan Amortization Schedule — Generate a month-by-month payment, principal, interest, and balance schedule
- Time Duration Calculator — Calculate elapsed time between two date-times after breaks
Everything above runs inside this page. Age Calculator needs no account, no upload, and no server round trip — close the tab and nothing is left behind.
年齡計算器能做什麼
輸入出生日期與目標日期，工具會算出精確的年、月、日年齡，以及兩個日期之間的總天數。計算方式是逐月推進而非直接除以 365，因此閏年、28 天的二月與 31 天的月份都能正確處理。
什麼時候用得上
- 人資與入學作業：資格常以某個截止日當天的年齡認定，而非以今天計算。
- 填寫需要「足歲幾年幾個月」的表單，例如簽證、保險或醫療文件。
- 統計某項資產、合約或試用期實際已經經過的天數。
使用步驟
- 在第一欄選擇出生日期。
- 設定第二個日期，預設為今天，也可改成任一日期。
- 按下計算。
- 在結果區查看年、月、日與總天數。
精確度、限制與實務建議
- 足歲年齡會捨去未滿的月份，所以差一天生日的人仍會顯示前一個歲數。
- 年月日的拆分與日期先後有關；若目標日期早於出生日期，年齡沒有實際意義。
- 總天數計的是日曆天，含週末與假日，也不會針對時區或時刻做調整。
常見問題
閏年會算進去嗎？
會。2 月 29 日視為實際日期；出生於該日者在平年一般依民間慣例視為 3 月 1 日增歲。
可以算過去某天的年齡嗎？
可以。把第二個日期設成過去任一天，即可得到當時的年齡，適合回溯資格審查。
總天數為什麼比想像中多？
總天數是兩日期之間完整的日曆天數。二十年含五個閏日，實際超過 7,300 天。
本站相關工具
以上步驟全部在這個頁面內完成，年齡計算器 不需要註冊、不上傳檔案、也不經過伺服器，關閉分頁後不會留下任何資料。