Age Calculator

Free Online Tool

Find Out Exactly How Old You Are

Pop in your birth date and get your exact age in years, months, days, even down to the second. Works for age gaps and pet years too.

Your date of birth

Calculate age as of

Results

Pick your date of birth to see your age.

Free online birthday calculator

This tool takes one date, your birthday, and works out exactly how old you are down to the day. Not an estimate, not a rounded-off guess. Just years, months, and days, plus the running totals most people never bother to check: total days alive, total weeks, total hours, and a seconds counter that keeps climbing while you watch it.

It is the kind of thing you do not need until you suddenly do. A school enrollment form asking for age as of September 1. A retirement planner that wants your exact age in months. An insurance form that will not accept about 40. Even just proving a point in an argument about who is actually older. Counting months and days by hand is where most people get it wrong. This skips that step entirely.

Why people actually use this

Junaid Farooq built this after getting tired of guessing. Here is when an exact age calculation actually matters:

  • Filling out forms. School applications, visa paperwork, insurance claims, and medical records all want your age written a specific way. Getting it wrong slows everything down.
  • Legal deadlines. Retirement eligibility, minimum age requirements, age-of-majority dates. These are not close enough situations. One day off can disqualify you.
  • Genealogy research. When you are tracing family history, you need to know exactly how old someone was on a specific date. Census records, marriage licenses, and military records all hinge on precise age.
  • Settling arguments. I am older by three months. No, it is four. This ends the debate with math, not opinions.
  • Just curiosity. There is something oddly satisfying about knowing you have been alive for 15,000+ days, or watching your age in seconds tick up live.

Calculate age by date of birth

Most people just want the basic answer: birth date in, current age out. That is the default here. Behind the scenes, the math follows real calendar rules, the same approach used on government forms and medical charts, not a simplified version that is close enough.

You are not locked into today either. Switch the calculate-as-of date to any day you need, and the tool works out age as of that date instead. Useful for school cutoff dates, immigration paperwork, or figuring out how old a relative was on a specific day for a family tree.

Date difference between two birthdays

Switch to the Age Difference tab and you are no longer measuring from today. You are measuring between any two dates you pick. People use this to check the age gap in a relationship, work out how many days sit between two project milestones, or settle how far apart two events actually were. You get the answer as years, months, and days together, plus a single flat day count for when you need one clean number.

How to calculate age manually

Sometimes you want to check the math yourself, or you are filling out a form that will not take a tool's output directly. Here is the manual method:

  1. Write down today's date and the date of birth in year-month-day order.
  2. Subtract the birth year from the current year.
  3. Check whether the birthday has actually happened yet this year. If not, subtract 1 from that number.
  4. For the months, subtract the birth month from the current month. If that is negative, add 12 and take away one more year from your total.
  5. For the days, subtract the birth day from the current day. If that goes negative, borrow from the previous month using its real length: 28, 29, 30, or 31 days, not a flat 30.

Example: someone born March 14, 1979, checking their age on July 19, 2026. Years: 2026 minus 1979 equals 47 (birthday already passed this year). Months: July minus March equals 4. Days: 19 minus 14 equals 5. Final answer: 47 years, 4 months, 5 days.

The Excel formula that does the same thing

Prefer to work it out in a spreadsheet? Excel's DATEDIF function does the same calendar-based math this tool runs on. Drop the birth date into cell A1, then use:

=DATEDIF(A1,TODAY(),"Y") & " years, " &
DATEDIF(A1,TODAY(),"YM") & " months, " &
DATEDIF(A1,TODAY(),"MD") & " days"

One catch worth knowing: DATEDIF is a legacy function Microsoft never fully documented, so it will not show up in Excel's formula autocomplete. It still works. Microsoft just never updated the help files.

Why this tool over the others?

Most sites give you one number and make you dig for the rest. Here, everything shows up at once: years, months, days, weeks, hours, and a seconds counter that is still running while you read this.

Other tools make you click between tabs. This does not. Other tools round to the nearest year. This gives you the exact breakdown. Four tools live on this one page: age from a birth date, age difference between two dates, pet age in human years, and working backward from a known age to find a birth date. Results copy with one click, and you can share a link straight to your calculation.

Nothing gets sent anywhere. The math runs in your browser, so there is no sign-up, no download, and no server logging your birthday.

About this tool

Built by Junaid Farooq after getting tired of tools that gave one number and hid everything else. This page shows years, months, days, weeks, hours, and seconds in one place, plus age gaps, pet years, and a date-of-birth lookup, without jumping between five different sites.

Every calculation runs in your browser using the same date math Excel and government forms rely on. Nothing you type is stored, sent to a server, or logged anywhere. Found a bug or want a feature added? Get in touch.

Last updated: July 2026

Questions people actually ask

Common questions about calculating age, leap years, and age differences.

How do I calculate my age from my date of birth?

Subtract your birth year from the current year. If your birthday has not happened yet this year, subtract one more year from that total. Then count the months and days separately using the same subtract-and-borrow method. This tool does all of that automatically. You just get the finished answer.

Can I calculate my age on a specific date?

Yes. Instead of leaving the calculate-as-of field on today, pick any date, past or future, and the tool works out your age as of that day. Use this for school enrollment cutoffs, immigration age requirements, or figuring out how old you will be on a future date like a wedding or retirement.

How does this handle leap years?

Leap years are built into the calendar math, not added as an afterthought. If someone's birthday is February 29, this tool treats it as February 28 in non-leap years for counting elapsed years, the same convention most legal and administrative systems use, while still calculating the exact day count correctly underneath.

What is chronological age?

Chronological age is the time that has passed since birth, measured in the calendar: years, months, and days. It is different from biological age, which estimates how old a body seems rather than how long a person has actually been alive. When a form or a doctor asks for your age, chronological age is what they mean.

How is Korean age different from international age?

Korean age starts at one, not zero, on the day someone is born, and everyone's age increases together on New Year's Day instead of on individual birthdays. Depending on birth month, that can put Korean age one or two years ahead of the international age most of the world uses. Toggle Also show Korean age to see both numbers at once.

How do I calculate age difference between two people?

Switch to the Age Difference tab, enter both birth dates, and the calculator returns the gap as years, months, and days, plus a flat day count if you need one number instead of three. It works the same way whether the gap is a few months or several decades.

How accurate is this online tool?

It is accurate to the day, using real calendar date math rather than a simplified days-divided-by-365 estimate. Leap years, varying month lengths, and the borrow-a-month logic are all handled correctly. The one thing it cannot account for is a wrong birth date typed in.

How do I calculate age in Excel?

Put the birth date in a cell, then wrap it in Excel's DATEDIF function with "Y", "YM", and "MD" as the unit arguments to pull out years, months, and days separately. The full formula is in the Excel section above. It is the same calendar-based approach this tool uses, just typed out manually.

Is my data safe?

Yes. Everything runs in your browser using JavaScript. Your birth date never leaves your device. There are no servers processing your information and no account required. You can disconnect from the internet after loading the page and the calculator still works.

Can I use this for my pet?

Yes. Click the Pet Age tab, choose dog or cat, and enter how many years old your pet is. The tool converts to human-equivalent age using the standard veterinary formula, not the old seven dog years equals one human year shortcut.