What this age calculator does
This age calculator turns a single date of birth into your exact age and a whole picture of the time you have lived. Enter the day you were born and it shows your age down to the year, month, and day — and, if you watch, ticking on by the second.
It goes well beyond a plain number. You get the day of the week you were born, a countdown to your next birthday, your age expressed in total months, weeks, days, hours, and seconds, and a few things you probably have never worked out, like your age on the other planets or the date of your golden birthday.
How age is calculated
Working out an age looks simple but has two traps. The method is to subtract the birth date from today, then borrow correctly when the days or months come up short.
Counting years, months, and days
Start from the birth date and count whole years until you are one year short of today, then add the leftover months and days. The day count has to borrow the length of the actual calendar month, which is where mistakes creep in by hand.
Leap years
Every four years February gains a day, and the calculator accounts for that automatically. It is the main reason a quick “today’s year minus birth year” can be a day or two off.
Your age on a specific date
Age is not only a “today” question. You might need your age on a past date for a form, or your age on a future date for planning. The calculator lets you set any date and recalculates your exact age as of that day, which also answers questions like how old you were when a particular event happened.
The day of the week you were born
Most people never learn which weekday they were born on. The calculator names it, along with the old “Monday’s child” rhyme, so a Tuesday baby is full of grace and a Saturday baby works hard for a living.
Your next birthday and your golden birthday
You will see how many days remain until your next birthday, which weekday it lands on, and the age you will turn. There is also your golden birthday — the year your age matches the date you were born on, such as turning 25 on the 25th — which only happens once in a lifetime.
Your pets have an age too — counted differently
Once you have your own age, it is natural to wonder about the other members of the household. Pets age on a completely different clock, and the old “one year equals seven” shortcut is a myth for both cats and dogs. A cat races to roughly fifteen human years in its first year, and dogs age at a pace that depends heavily on their size. If you want your pet’s real age in human years, the dog age calculator works it out by breed size, and the cat age calculator uses the life-stage method vets actually use.
Related calculators
This is the hub for a set of date and age tools. To measure the gap between two birth dates, use the age difference calculator. For an exact age as of a test or evaluation date, see the chronological age calculator. To count the time between any two dates, try the days between dates calculator. And for a premature baby’s age adjusted to the due date, use the corrected age calculator.
frequently asked questions
How do I calculate my exact age?
Subtract your birth date from today, counting whole years first, then the leftover months and days, borrowing the real length of each calendar month. The calculator above does this instantly and keeps your age accurate to the day, including leap years.
How old am I if I tell it my birthday?
Enter your date of birth and the calculator returns your age in years, months, and days, plus totals in weeks, days, hours, and seconds, and the day of the week you were born.
Can I find my age on a date that is not today?
Yes. Set any date — past or future — and the calculator gives your exact age as of that day, which is useful for forms or for working out how old you were when something happened.
What day of the week was I born on?
The calculator names the weekday for your birth date. It is fixed by the date itself, so it never changes, and it is something most people have never looked up.
What is a golden birthday?
Your golden birthday is the year your age matches the day of the month you were born — turning 14 on the 14th, for example. It happens only once, and the calculator shows when yours is or was.
How do I calculate my pet’s age in human years?
Not with the “times seven” rule, which is a myth. Use the dog age calculator, which converts by breed size, or the cat age calculator, which uses the life-stage method, for an accurate human-years figure.
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