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Age Calculator

What is the Age Calculator?

The Age Calculator works out the exact time between a date of birth and today, or between any two dates, in years, months and days, and also as a total in days, weeks, hours and minutes. It shows the day of the week you were born, how many days until your next birthday, and handles leap years and month lengths properly, which is where most quick calculations go wrong. Use it for age on forms, contract periods, project durations or countdowns. It runs in your browser.

How to use it

Enter the date of birth (or the start date).
Leave the second date as today, or set an end date.
Read the age in years, months and days, the totals, and the next-birthday countdown.

Why calculators disagree

“Two months” is not a fixed number of days, so there is more than one defensible way to count. This tool counts whole years first, then whole months, then the remaining days, using the actual lengths of the months involved, which matches how age is understood legally and in everyday speech. Someone born on 31 January is one month old on 28 February (or 29th in a leap year), not on 3 March. Leap-day babies age a year on 28 February in non-leap years for most legal purposes, and on 1 March in a few jurisdictions. The counting rules, how to do it by hand, and the edge cases are in how to calculate your exact age, and why calculators disagree.

Other uses

Duration of a contract, lease or warranty.
Days until a deadline or an event.
Age at a specific past date (for records, eligibility, sports categories).
Time elapsed since a start date in a project report.

Related tools

Convert the result into other units with the Unit Converter, convert a birth time across zones with the Time Zone Converter, or express an age as a percentage of a milestone with the Percentage Calculator.

Read the guide

How to Calculate Your Exact Age in Years, Months and Days (and Why Calculators Disagree)

Exact age in years, months and days is harder than it looks: month lengths, leap days and country conventions all change the answer. Here's how it's calculated, why two tools can differ, and the milestones worth knowing.

Frequently asked questions

Does it handle leap years?

Yes. Leap days are counted in the day totals and month lengths are taken from the real calendar.

Can I calculate between two past dates?

Yes. Set both dates.

Is the result the same as the legal age?

For almost all purposes, yes. A few jurisdictions treat the day before the birthday as the day you turn a year older; check local rules for legal thresholds.