Age Calculator

Use it when your task matches one of these common needs: Find exact age today or on a future date. Calculate age for forms, school records, birthday planning, or quick checks. It works best when you already know a real birth date and the exact as-of calendar date you want to check.

In plain language: The calculator compares two valid calendar dates, subtracts full years, then remaining months and days. It also counts total days using UTC calendar dates. The examples on the page are there so you can compare your inputs with a worked example before copying the answer.

Birth date: the birth or start date you want to compare, in YYYY-MM-DD form. As-of date: the calendar date you want to calculate age on, not always today. Total days: the full day count between those two dates, separate from calendar years and months. Next birthday: the next matching month and day after the as-of date.

Read the headline answer, then check the supporting lines and examples to understand how the calculator got there. If one input changes, rerun the tool and compare the new answer instead of guessing.

Check the as-of date carefully. Legal, school, insurance, and age-restricted decisions can use their own cutoff rules. Also check the birth date, as-of date, leap-day rule, and any official cutoff date because one day can change the answer.

It compares date to date. If the birth date and as-of date are the same calendar day, age is 0 days. If the as-of date is tomorrow, it counts 1 full day.

Calendar age uses completed years, then months, then days. Total days is one continuous count. They differ because months and years do not all have the same number of days.

The calculator treats February 29 as the actual birth date. For official forms, schools, insurance, and age limits, check the rule that says whether a non-leap year uses February 28 or March 1.

Use it as a quick check only. Legal age, school eligibility, sports groups, insurance, and age-restricted services may define their own cutoff date or leap-day rule.

Use the browser date picker when it appears. The stored value is a YYYY-MM-DD date, which keeps month and day order clear across different countries.

It is the number of days from the as-of date to the next birthday date. If the birthday is today, the countdown is 0 days.

No. The calculator runs in your browser tab. Your recent answers stay only on the page while you use it, and they are not sent to a server.