How to Calculate Your Exact Age in Years, Months and Days

To calculate your exact age, open the Age Calculator and enter your Date of birth — it instantly shows your age in years, months and days, along with your total months, weeks, days and hours lived, the weekday you were born on, and how long until your next birthday.

What the Age Calculator does

Age isn't just "today's year minus your birth year" — that overcounts by a year until your birthday actually arrives, and it says nothing about months, days or birthdays. The Age Calculator works out the real calendar difference between two dates: it counts whole years, then whole months within the current year, then whatever days are left over, borrowing days from the previous month when needed (the same way you'd count on a calendar by hand). From that it derives everything else — total months, total weeks and leftover days, total days, total hours, the day of the week you were born, and the number of days until your next birthday.

How to calculate your age with Toolbench

1. Open the Age Calculator.
2. Enter your Date of birth.
3. Leave Age on set to today's date to see your current age, or change it to any other date to see how old you were (or will be) on that date.
4. Read your age in the large result box as "X years, Y months, Z days," then check the rows below for total months, total weeks and days, total days, total hours, the weekday you were born on, and your next birthday.

Example: born June 15, 1990

With Date of birth set to 1990-06-15 and Age on left at today's date:

Date of birth	1990-06-15
Age	36 years, 3 months, 23 days
Total months	435
Total weeks	1,894 weeks, 6 days
Total days	13,264
Total hours	318,336
Born on a	Friday
Next birthday	In 250 days · Tuesday

Someone born on June 15, 1990 has lived 13,264 days — that's 1,894 full weeks plus 6 extra days, or 318,336 hours. Their birthday fell on a Friday, and their next one is 250 days away, landing on a Tuesday.

Example: how old was I on a specific date?

The Age on field doesn't have to be today. Set Date of birth to 1985-03-22 and Age on to 2020-01-01, and the calculator answers "how old was this person on January 1, 2020?": 34 years, 9 months, 10 days, or 12,703 total days. This is the field to use for figuring out someone's age as of a past event, a legal deadline, or a future date like a planned retirement day.

Example: when your birthday is today

If Age on lands exactly on your birthday, the math still works — the year/month/day difference comes out to a whole number of years with 0 months and 0 days (for example, born 2000-10-08, checked on 2026-10-08, gives 26 years, 0 months, 0 days), and the Next birthday row switches from a day count to simply "Today!".

Tips and common mistakes

• Years-minus-years isn't your age. Subtracting birth year from the current year overstates your age for every day before your birthday has happened this year — the calculator accounts for whether your birthday has occurred yet.
• "Age on" must be after "Date of birth." The calculator shows an error — "Age on" must be after the date of birth. — if you set it earlier.
• Months and days borrow from the calendar, not a fixed 30-day month. If the day-of-month count goes negative, the calculator borrows days from the actual length of the previous month, so the result matches counting by hand on a calendar.
• "Total weeks" and "Total days" are two views of the same number. Total weeks shows the leftover days (e.g., "1,894 weeks, 6 days"), while Total days gives the same span as one plain number (13,264).
• Use "Age on" for more than just today. Set it to any past or future date to find your age at a specific moment — a wedding date, a graduation, or a milestone birthday you're counting down to.

Related tools

• Days Calculator — days, weeks and business days between any two dates.
• Month Calculator — months between two dates, or a date plus or minus N months.
• Hours Calculator — hours worked between two times, minus breaks, with pay.

Frequently asked questions

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

Find the year difference between the two dates, then the month difference, then the day difference. If the day difference is negative, borrow a month and add the number of days in the previous calendar month; if the month difference is then negative, borrow a year and add 12 months. This gives the precise calendar age rather than a rough year count.

Why is my age in years alone not accurate?

Subtracting birth year from the current year assumes your birthday has already happened this year. If it hasn't, that number is one year too high — the Age Calculator checks whether the birthday has passed and adjusts for it automatically.

Can I find out how old I'll be on a future date?

Yes. Set Date of birth to your birth date and Age on to the future date — the calculator will show your exact age as of that day, including how many total days, weeks and months that will be.

What does the "Next birthday" row mean?

It's the number of days from your Age on date until your next birthday, plus the day of the week that birthday falls on. If your Age on date is your birthday, it shows "Today!" instead.

Is my birth date sent to a server?

No. The calculation runs in your browser as you type. If you're signed in, your inputs sync privately to your account; if you're signed out, nothing is saved anywhere.