Age Calculator

What is age calculator?

An age calculator works out how much time has passed between a birth date and another date, usually today. It gives the answer in the units people actually use: years, months and days. It can also show the same span as total months, weeks, days or hours.

People use it for school and job forms, visa and insurance applications, retirement planning, sports eligibility, and plain curiosity. Counting by hand is easy to get wrong because months have different lengths and leap years add a day.

How to use the age calculator

1. Choose your date of birth.
2. Leave the second date as today, or pick any date in the past or future to see your age on that day.
3. Press Calculate to see your age, total days lived, the weekday you were born and the time until your next birthday.

How the age calculator works

The tool subtracts the birth date from the chosen date field by field. If the day of the month is smaller, it borrows days from the previous month. If the month is smaller, it borrows a year. Total days use calendar dates with no time zone shift, so the result does not change with where you are.

Worked example

Common uses of the age calculator

• Filling in school, job, visa or insurance forms that ask for your exact age.
• Checking whether someone meets a minimum or maximum age for a sport, exam or program.
• Planning retirement or pension dates from a birth date.
• Finding how many days old you are for a milestone such as 10,000 days.
• Working out the age of a pet, a company or a building from its start date.

Tips and common mistakes

Use the second date field to answer questions such as how old will I be on the day of an exam, or what was my age when I joined a company. Enter the future or past date there.

Some countries count age differently. East Asian age reckoning, for example, adds a year at birth. This tool uses the international standard, where you turn one year old on your first birthday.

Background: what to know before you rely on it

Age has been counted in different ways across history. Many East Asian cultures once counted a baby as one year old at birth and added a year every lunar new year. Today most countries use the international method, where age rises by one on each birthday. Legal systems rely on exact age for voting, driving, work and benefits, so a precise calculation matters. Because months are uneven, the cleanest way to count is to subtract field by field and borrow from the previous month, which is what this tool does. If your birthday is on 29 February, most places treat 28 February or 1 March as your birthday in non leap years.

Private, free and fast

This tool runs entirely in your browser. What you type or choose is not uploaded to a server and is not saved after you close the page, which keeps it fast and private. It is free to use as often as you like. See more in all date and time tools, or browse the full list of tools.

Related tools

Results are for information and education. For legal, financial, medical or security decisions, check with a qualified professional. For legal deadlines, confirm how your contract or court counts days.