Age Calculator

Know your exact age

Enter a date of birth and the calculator instantly shows the precise age in years, months and days, correctly accounting for leap years and varying month lengths. You can also set a custom 'age at' date to find how old someone was, or will be, on any specific day.

What it shows

• Exact age in years, months and days
• Total months, weeks, days and hours lived
• Number of days until the next birthday

Key features at a glance

• Exact age in years, months, and days from a date of birth
• Total months, weeks, days, and hours lived
• Custom 'age at' date to find age on any past or future day
• Countdown of days until the next birthday
• Correctly handles leap years and varying month lengths
• Runs entirely in your browser — your date of birth never leaves your device

How exact age is calculated

Calculating age precisely is trickier than subtracting two years, because months have different lengths and leap years add an extra day every four years. The correct method counts complete years from the birth date, then complete months since the last birthday, then the remaining days — borrowing days from the previous month when the day-of-month has not yet been reached, just as you would when subtracting by hand.

This calculator does that borrowing automatically, so someone born on 31 January measured on 1 March gets an accurate day count rather than a rounded estimate. It also accounts for February's variable length and for leap days, which is why it can confidently tell you an age down to the exact day across any span of years.

Why measure age in months, weeks, and days

Different situations call for different units. Parents track a baby's age in weeks and then months because development happens so quickly in the early years. Medical dosing, developmental milestones, and many official forms ask for age in completed months rather than years, where a rounding error could matter.

Expressing a lifespan in total days or hours also makes abstract durations vivid — it turns 'a few decades' into a concrete, surprisingly large number. Seeing every unit at once lets you pick whichever is most meaningful for your purpose, whether that is a precise legal age, a fun milestone like your ten-thousandth day, or simply the countdown to your next birthday.

Tips for using the age calculator

• Set the 'age at' date to find how old someone will be on a future occasion
• Use it to check eligibility thresholds that depend on an exact date
• Measure a baby's age in weeks or months for milestone tracking
• Count down to a birthday to plan parties and reminders
• Compare two people's ages by running the calculator for each

Why choose our age calculator?

Our calculator is completely free with no signup, no limits, and no subscription. It runs entirely in your browser, so results are instant, it works offline, and your date of birth — a piece of personal information — is never sent to a server.

It is one of more than 200 free tools on ToopTools, and you can pin it to your My Workspace, a personalized workspace where you keep the tools you use most in a single dashboard. Beside the date difference and other date tools, it makes any age or duration question quick to answer.

Common use cases

People use the age calculator to find their exact age for forms and applications, to check whether they meet an age requirement on a specific date, and to settle the perennial question of exactly how old someone is. Parents use it to track an infant's age in weeks and months.

It is also popular for fun milestones — discovering the day you turn 10,000 days old, counting down to a birthday, or working out a historical figure's age at a key event. Because it accepts any 'age at' date, it works equally well for past and future calculations.

Is the age calculator free?

Yes. It is completely free with no account, no sign-up, and no usage limits. Calculate as many ages as you like at no cost.

Does it account for leap years?

Yes. The calculator correctly handles leap years and the differing lengths of months, so the age in days is accurate across any span, including birth dates on 29 February.

Can I calculate age on a future or past date?

Yes. Set the 'age at' date to any day you choose, and the calculator shows how old the person was, or will be, on that exact date rather than today.

How is the next birthday countdown calculated?

It finds the next occurrence of your birth day and month after the chosen reference date and counts the days remaining, accounting for whether this year's birthday has already passed.

What if someone was born on 29 February?

The calculator handles leap-day birthdays correctly. In non-leap years it counts the birthday at the appropriate boundary, so the age in completed years stays accurate.

Can I find out how many days old I am?

Yes. Alongside years, months, and days, the calculator shows the total number of days you have lived, as well as total weeks and hours, so you can see your age expressed entirely in days at a glance.

Does the age calculator work for any birth year?

Yes. It handles birth dates across any range of years, applying leap-year and month-length rules throughout, so it works equally well for recent births and dates from many decades ago.

Is my date of birth kept private?

Yes. The calculation runs entirely in your browser and nothing is uploaded, so your date of birth stays on your device and the tool works without an internet connection.

How do I calculate my exact age in years, months, and days?

Enter your date of birth and the calculator instantly shows your exact age broken down into years, months, and days, accounting for leap years. You can also set a target date to find your age on any past or future day.

Does the age calculator work offline?

Yes. The calculation runs entirely in your browser, so once the page has loaded the tool works without an internet connection, and your date of birth is never uploaded — it stays private on your own device.