Age Calculator
Calculate your exact age in years, months, and days. Find out how many total days, weeks, hours, and minutes you have lived — plus how many days until your next birthday.
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MM/DD/YYYY
01/01/2025
Enter your date of birth to calculate your age
Age calculator. Exact age in years, months, and days.
Enter your date of birth and the age calculator returns your exact age in years, months, and days, handling leap years and uneven month lengths for you. It also shows total days, weeks, hours, and minutes lived, plus the countdown to your next birthday.
What Is an Age Calculator?
Chronological age is the time elapsed between your date of birth and a reference date, expressed as the calendar difference in completed years, months, and days. Because calendar months run 28 to 31 days and leap years add a February 29, you cannot simply divide total days by 365 to get it; the count is taken month by month from your birthday forward, so the result matches the intuitive answer to "how old am I?" down to the day. An age calculator runs that comparison for you and can also express the same span in total days, weeks, hours, and minutes lived.
Beyond simple curiosity, knowing your precise age matters in many practical situations. Parents track infant age in weeks and months for pediatric checkups. Job applicants, passport renewers, and voters need to verify they meet age requirements on a specific date. Insurance companies and government agencies calculate age to the day for eligibility determinations. An age calculator eliminates the mental math of counting across unequal months, leap years, and calendar boundaries.
Our age calculator computes your exact age from any birth date to any target date, breaks it down into years, months, and days, and also shows your total days lived, weeks lived, hours, minutes, and how many days remain until your next birthday.
How to Use the Age Calculator (and Do the Math by Hand)
Using the calculator takes seconds: enter your date of birth, then either leave the reference date on today or set it to any past or future date you want your age measured against. The result appears instantly as completed years, months, and days, alongside your total days, weeks, hours, and minutes lived and a countdown to your next birthday.
If you want to check the math yourself, age is found with long subtraction on the two dates, the same borrowing you learned for column subtraction applied to day, month, and year:
1. Write the reference date and your birth date as year-month-day.
2. Subtract the birth day from the reference day. If the reference day is smaller, borrow one month: add the number of days in the previous calendar month, then subtract.
3. Subtract the birth month from the reference month (after any borrow). If it is now smaller, borrow one year: add 12 to the month, then subtract.
4. Subtract the birth year from the reference year (after any borrow). That gives the completed years; the leftovers from steps 2 and 3 are your months and days.
Worked example (as of July 15, 2026): someone born on June 20, 1990. The reference day 15 is smaller than the birth day 20, so borrow from June (30 days): 15 + 30 = 45, and 45 - 20 = 25 days. The month 7 drops to 6 after the borrow, and 6 - 6 = 0 months. The year is 2026 - 1990 = 36. The result is 36 years, 0 months, and 25 days; the zero-month value simply means the June birthday has already passed but a full month of the next year has not yet gone by.
For the totals, the calculator counts the days that have actually elapsed between the two dates (the birth day itself is not counted), then divides by 7 for weeks and multiplies by 24 for hours. Someone born on January 1, 2000, for instance, has lived 9,692 days as of July 15, 2026, which is 1,384 weeks and 232,608 hours.
Age Calculation Formula
- = Current year (or target year)
- = Birth year
- = Current month (adjusted after borrowing)
- = Birth month
- = Current day (adjusted after borrowing)
- = Birth day
This formula uses borrowing (just like long subtraction in arithmetic) to handle cases where the current day or month is smaller than the birth day or month:
The number of days borrowed depends on the length of the previous calendar month (28, 29, 30, or 31 days). February contributes 28 days in common years and 29 days in leap years. A year is a leap year if it is divisible by 4, except for century years, which must be divisible by 400. This means 2000 and 2024 are leap years, but 1900 and 2100 are not.
For total days lived, the calculation sums the actual days in every month between the two dates, fully accounting for leap years:
Worked Age Examples (as of July 15, 2026)
How Many Days Have You Been Alive?
Say you were born on January 1, 2000 and want to know how many days you have lived as of July 15, 2026. The calculator returns an age of 26 years, 6 months, and 14 days, which works out to 318 months, or 1,384 weeks, or 9,692 days. In smaller units that is 232,608 hours, 13,956,480 minutes, and 837,388,800 seconds. Note that the total-days figure counts the days that have actually elapsed since birth, not the result of multiplying years by 365.
Leap-Day Birthdays: Born on February 29
A person born on February 29, 2000 (a leap year) is 26 years, 4 months, and 14 days old as of July 15, 2026, or 9,633 days. Because neither 2026 nor 2027 is a leap year, the calculator places the next birthday on March 1, 2027 (229 days away), when they turn 27. Legal conventions vary; some jurisdictions treat February 28 as the birthday in common years, but this tool follows the standard Gregorian behavior, where adding a year to February 29 rolls over to March 1.
Counting Down to the Next Birthday
Someone born on September 30, 1995 is 30 years, 9 months, and 15 days old as of July 15, 2026 (about 11,246 days). Because that year's birthday has not arrived yet, the calculator counts just 77 days until it falls on September 30, 2026, when they turn 31. Had the birthday already passed, the countdown would run to the anniversary in the following year instead.
Checking Age Eligibility for a Driver's License
A teenager born on March 10, 2010 wants to know whether they have reached the age of 18 needed for a full license. As of July 15, 2026 the calculator shows 16 years, 4 months, and 5 days (about 5,971 days), so they are not yet eligible. Their next birthday, March 10, 2027 (238 days away), brings them to 17, leaving a full year still to go before they turn 18.
What Happens Exactly on Your Birthday?
When someone born on July 15, 1985 uses July 15, 2026 as the reference date, their birthday itself, the calculator shows a precise 41 years, 0 months, and 0 days (14,975 days), and the countdown to the next birthday reads zero because today is the day. This shows that zeros in the month and day fields are a correct result, not an error.
Age Reference Table (as of July 15, 2026)
| Birth date | Age (y/m/d) | Total days | Total weeks | Next birthday |
|---|---|---|---|---|
| January 1, 2000 | 26 / 6 / 14 | 9,692 | 1,384 | January 1, 2027 (170 days) |
| June 20, 1990 | 36 / 0 / 25 | 13,174 | 1,882 | June 20, 2027 (340 days) |
| March 10, 2010 | 16 / 4 / 5 | 5,971 | 853 | March 10, 2027 (238 days) |
| February 29, 2000 | 26 / 4 / 14 | 9,633 | 1,376 | March 1, 2027 (229 days) |
| September 30, 1995 | 30 / 9 / 15 | 11,246 | 1,606 | September 30, 2026 (77 days) |
| July 15, 1985 | 41 / 0 / 0 | 14,975 | 2,139 | July 15, 2026 (today) |
Common Age-Calculation Mistakes
- Counting the birth day as day one. Total days measure the days that have elapsed between the two dates and do not include the day you were born, so a tally that starts at 1 reads one day too high.
- Treating every year as exactly 365 days. Roughly every four years adds a February 29, and ignoring those leap days compounds into a multi-day error across decades.
- Confusing your age with the number of days since a date. Age is expressed in completed years, months, and days, while the gap between two dates is a raw day count; they are two different measures that rarely match in your head.
- Adding months as a flat 30 days. Real months run 28 to 31 days, so a fixed 30-day shortcut drifts off by a day or two, which is the usual reason a manual answer disagrees with the calculator.
- Expecting February 29 to appear every year for a leap-day birthday. In common years there is no February 29, so this calculator advances the birthday to March 1 rather than to a date that does not exist.
Tips for Getting an Exact Age
- Always enter the full date of birth (day, month, and year). A birth year alone leaves two possible ages depending on whether the birthday has already passed.
- For eligibility deadlines such as school entry, driving, or retirement, set the reference date to the exact cutoff so you see your age on that specific day, not just sometime that year.
- To find how long until a milestone age or a special occasion, set a future reference date and read the day countdown the tool displays.
- Track an infant's age in weeks for the first three months, then switch to months, the same convention pediatricians use for growth and vaccination charts.
- This calculator uses the Gregorian calendar, the international civil standard. If your birth date is on a lunar or other calendar, convert it first, since the age can shift by a year or more.
- Save or screenshot the result when you need it for a form; the age is exact only for the reference date shown, and it changes the next day if that date is today.
Frequently Asked Questions About Age Calculation
How do I calculate my exact age in years, months, and days?
Subtract your birth date from the reference date using long subtraction: first the days (borrowing a month if the day comes up short), then the months (borrowing a year if needed), then the years. For example, someone born on June 20, 1990 is 36 years, 0 months, and 25 days old as of July 15, 2026. The calculator above does this instantly for any birth date.
How many days old am I?
Your age in days is the total calendar days between your birth date and the reference date. Someone born January 1, 2000 has lived 9,692 days as of July 15, 2026, about 1,384 weeks. Enter your date of birth above for an exact figure.
How do I calculate age from a date of birth?
Subtract the birth date from the target date component by component: days, then months, then years. The key step is borrowing: if the current day is less than the birth day, add the number of days in the previous month to the current day and reduce the month count by one. If the current month is then less than the birth month, add 12 months and reduce the year count by one. This gives an accurate age in years, months, and days without rounding errors.
What is the correct way to count months between two dates?
A complete month is counted when you pass the same day-of-month as the start date. For instance, from March 15 to April 15 is exactly 1 month, and from March 15 to April 14 is 0 months and 30 days. When the start day does not exist in the target month (for example, January 31 to February), the end-of-month is used as the boundary. This method keeps age expressed in months a whole number with a leftover in days.
How is age calculated for February 29 birthdays?
A leap-day birthday appears on the calendar only once every four years. In common years this calculator advances the birthday to March 1, because adding a year to February 29 rolls over to March 1. Someone born on February 29, 2000 is 26 years, 4 months, and 14 days old as of July 15, 2026, with their next birthday shown as March 1, 2027. Some jurisdictions instead treat February 28 as the birthday in common years. The odds of a February 29 birth are about 1 in 1,461.
How many days until my next birthday?
The calculator checks whether this year's birthday has passed. If not, it counts to that date; if it has, it counts to next year's. Someone born September 30, 1995 has 77 days until their birthday on September 30, 2026.
What is the difference between running age and completed age?
Completed age is the number of full years you have finished living, which is the standard in most Western countries. Running age is the year of life you are currently in, equal to your completed age plus one. For example, if you are 30 years old (completed age), your running age is 31. Some South and East Asian cultures use running age in daily life, while government forms and legal documents in the US typically use completed age.
How old will I be on a specific future date?
Enter your birth date and set the reference date to the future date you want to check; the calculator shows your exact age that day. This is handy for eligibility questions. A teenager born on March 10, 2010, for example, is 16 years, 4 months, and 5 days old as of July 15, 2026, so they are still short of the 18 needed for a full driver's license.
Is this age calculator free and accurate?
Yes. It runs in your browser at no cost and uses the same long-subtraction algorithm as official age reckoning, fully accounting for leap years and uneven month lengths, so results are accurate to the day. For legal or medical purposes, the relevant authority still confirms the final figure from your documents.
Why does my hand calculation differ from the calculator by a day or two?
The usual causes are treating every month as 30 days, overlooking a leap year, or counting the birth day itself in the total. This calculator counts the actual days between the two dates (excluding the birth day) and uses real month lengths of 28 to 31 days, so its result is more precise than mental math.