Age Calculator
This age calculator works out your exact age in years, months and days from your date of birth, plus the total days, weeks and hours you have lived. It uses today’s date unless you pick any other past or future date. Enter your date of birth below and press Calculate Age to see your result, your next birthday and how many days are left.
Quick answer: To calculate your age, subtract your date of birth from the date you want to check and count complete years first, then leftover months and days. Someone born on 15 May 1990 is 36 years, 4 months and 18 days old on 3 October 2026, which is 13,290 days. The calculator does this for any date.
How do you use the Age Calculator?
- Enter the date of birth. Pick the day, month and year of birth in the Date of birth field.
- Choose the date to check. Leave “Age on” as today, or change it to any past or future date, such as a birthday, deadline or cut-off date.
- Press Calculate Age. Read your exact age in years, months and days, plus total days lived and the countdown to your next birthday.
What is the formula, and what does a worked example look like?
Formula: Age = complete years + complete months + remaining days between the date of birth and the chosen date.
Example: Born 15 May 1990, checked on 10 March 2024: 33 years, 9 months, 24 days. The next birthday (15 May 2024) is 66 days away.
Method & source: Gregorian calendar rules; whole calendar months are added first, then leftover days. See how we test our calculators.
Next step: try days between two dates or business days until a deadline.
Worked examples for the Age Calculator
Each figure below was produced by the same code as the calculator, so you can enter the inputs and get the same result. Rates and thresholds are the ones on the official pages linked under “How it is calculated”.
Born 15 May 1990, age on 13 November 2026
Dates are day/month/year in the UK; the calculator takes a date picker value, so the order is never ambiguous.
- Whole years: 36 (the birthday in 2026 has already passed).
- Months and days after the last birthday: 36 years, 5 months, 29 days.
- Next birthday: 183 days away, turning 37.
Result: 36 years, 5 months, 29 days.
Born 4 July 1976 (written 7/4/1976 in the US), age on 31 December 2026
US dates are month/day/year, so 7/4 is July 4th; in the UK the same digits mean 7 April.
- Whole years: 50 on 4 July 2026.
- Remaining: 50 years, 5 months, 27 days on 31 December 2026.
Result: 50 years, 5 months, 27 days.
Born 29 February 2000, a leap-day birthday
In years that are not leap years the birthday is counted on 1 March.
- 28 February 2027: 26 years, 11 months, 27 days, one day before the birthday.
- 1 March 2027: 27 years, 0 months, 0 days, the observed birthday.
Result: The age goes up on 1 March, and the next-birthday panel uses the same date.
How is the Age Calculator calculated, and where do the rates come from?
Age is the calendar difference between the date of birth and the chosen date. The calculator counts whole years first, then whole months after the last birthday, then leftover days. It uses calendar months, not 30-day blocks, so 31 January to 28 February is counted as the days really in between.
Total days, weeks, months and hours are shown as well: total days is simply the number of days between the two dates, which is not the same as years × 365 because leap years add a day. The age can be checked on any date, past or future, so you can see how old someone will be on a deadline.
For a 29 February birthday the birthday is observed on 1 March in common years, in both the age and the next-birthday results. Some places and rules use 28 February instead; where a legal age matters, such as a pension date, use the official calculator linked below rather than any general tool.
- GOV.UK – Check your State Pension age – The official calculator for the date you reach State Pension age; it is reviewed and can change.
What are the common mistakes and edge cases?
- Typing the date of birth in the wrong order. A date picker avoids this, but if you copy a date from a form, check whether it is day/month or month/day before you enter it.
- Counting the birth year minus the current year. That is only right after the birthday has passed in the current year; the calculator checks month and day.
- Dividing total days by 365 to get years. Leap days make that slightly wrong, and the error grows with age.
- Assuming a legal age follows the same rule everywhere. Age-based entitlements such as State Pension age have their own rules and can change.
- Forgetting that 'age on a date' needs the target date. The default is today; change it to check an exam entry date, a policy start or a cut-off.
More in this category: Dates & Time calculators.
How do you work out your exact age?
An age calculator works out how old someone is from their date of birth. Instead of a rough “about 34”, it gives the exact number of years, months and days that have passed, along with the total days, weeks and hours lived.
Most tools only answer “how old am I today?”. This age calculator on a specific date lets you pick any day you like, so you can check how old you were at a milestone, how old you will be on a future date, or how old someone is for a form, visa or school-entry cut-off.
How are years, months and days counted from a birth date?
Enter a date of birth and the date you want to measure to. The calculator compares the two calendar dates and counts complete years first, then leftover months, then leftover days.
- Exact age: Full years, months and days between the birth date and your chosen date.
- Total time lived: The same span shown as months, weeks, days and hours.
- Next birthday: The date, weekday and number of days remaining until you turn a year older.
- Leap-day births: Birthdays on 29 February are observed on 1 March in common years.
- Shareable result: Copy a link that reopens the calculator with the same dates filled in.
Everything is calculated in your browser using calendar dates only, so time zones and daylight-saving changes never shift the answer.
When does an exact age matter?
Age is more than a number on a birthday card. Many official and everyday decisions depend on precise age, sometimes to the day.
- Check eligibility for school entry, driving, voting, insurance or retirement schemes.
- Complete applications and legal forms that ask for age on a particular date.
- Plan birthdays, anniversaries and milestone celebrations with a countdown.
- Track a baby’s development in months and weeks rather than years.
- Settle friendly arguments about who is older, and by how many days.
Whether you need an exact age for paperwork or just curiosity, calculating it from the birth date and a chosen date removes any guesswork.
Worked walkthrough: age on a chosen date
Priya was born on 3 March 1992 and wants to know her age on 15 June 2026. The calculator first counts complete years (34, reaching 3 March 2026), then whole months from that date (3, reaching 3 June 2026), then the remaining 12 days. Her exact age is 34 years, 3 months and 12 days, or 12,522 days in total. Her next birthday is Wednesday 3 March 2027, when she turns 35 – 261 days away. Changing the “age on” date to 1 January 2030 instantly shows how old she will be then, with no manual counting.
Common mistakes when working out an age
- For legal or school cut-off dates, set the “age on” date to the exact cut-off day rather than today, so you see the age the rule will actually use.
- Different countries count age differently (some traditions count a newborn as one year old). This tool uses the international convention of completed years.
- Use the total days figure to compare two people’s ages precisely – the person with more total days is older, even if both are the same age in years.
- If someone was born on 29 February, remember their birthday is observed on 1 March in common years here; some places use 28 February, so check any official rule.
- Copy the share link before you change the dates if you want to send a specific calculation to someone – the link stores both dates.
How an exact age is counted
Chronological age is the time that has passed since birth, counted in complete calendar units. The calculator first counts whole years from the date of birth, then whole months, and finally the days that are left over. Someone born on 15 August 1990 is 39 years, 4 months and 17 days old on 1 January 2030.
Month-ends need a rule. When the birth day does not exist in a shorter month, the last day of that month is used. A person born on 31 January 2020 reaches one full month on 29 February 2024, so on that day they are 4 years, 1 month and 0 days old. A day later, on 1 March, the display moves to 4 years, 1 month and 1 day.
Why the “age on” date matters
Today’s age is only one of the questions people ask. Forms, schools, sports leagues and insurers often ask for your age on a fixed date such as the first day of term, the closing date of an application or the start of a season. Setting that date in the calculator gives the age that rule will actually use, in the past or the future. The rules themselves differ between organisations, so treat the result as the calculation and check the official cut-off wording.
The same idea works for milestones. Someone born on 1 January 2000 turns 10,000 days old on Wednesday 19 May 2027, a date you can find by counting forward or by checking the total days lived at different “age on” dates.
Birthdays on 29 February
People born on a leap day have a real birthday only in leap years. In common years this calculator observes the birthday on 1 March, so for someone born on 29 February 2000 the countdown from 27 February 2027 shows a birthday two days away, on Monday 1 March 2027, when they turn 27. Some places treat 28 February as the legal birthday instead, which is why official documents should be checked when the exact day matters.
Age in days, weeks, months and hours
Alongside the years-months-days result, the calculator shows the same span as totals. The person born on 15 August 1990 has lived 14,384 days by 1 January 2030, which is 2,054 full weeks, 472 months and 345,216 hours. Totals are the best way to compare two people precisely: the one with more days lived is older, even when both are the same age in years.
If you need the gap between two dates that are not a birth date, the date difference calculator gives the same breakdown for any pair of days.
Worked examples: age on 9 November 2026 for five birth dates
These results use the same function as the calculator, so you can check any of them by entering the date of birth and 9 November 2026 as the “age on” date. They show the awkward cases: a leap-day birth, a birthday today and a birthday in late December.
| Date of birth | Age on 9 Nov 2026 | Total days lived | Total months | Next birthday |
|---|---|---|---|---|
| 1 Jan 2000 | 26y 10m 8d | 9,809 | 322 | 53 days (turning 27) |
| 29 Feb 2000 | 26y 8m 8d | 9,750 | 320 | 112 days (turning 27) |
| 15 Aug 1990 | 36y 2m 25d | 13,235 | 434 | 279 days (turning 37) |
| 31 Dec 2010 | 15y 10m 9d | 5,792 | 190 | 52 days (turning 16) |
| 9 Nov 2016 | 10y 0m 0d | 3,652 | 120 | Today |
The person born on 9 November 2016 is exactly 10 years 0 months 0 days old on that date, and the calculator reports a birthday that falls on the chosen date as “Today”. The leap-day birth on 29 February 2000 shows 26 years 8 months 11 days, and their next birthday is observed on 1 March 2027 because 2027 has no 29 February.
When do you turn 10,000, 15,000 and 20,000 days old?
Day counts make good milestones, and the calculator’s total-days figure tells you how far away they are. Counting forward from each date of birth:
| Date of birth | 10,000 days old | 15,000 days old | 20,000 days old |
|---|---|---|---|
| 1 Jan 1980 | Saturday 19 May 2007 | Monday 25 January 2021 | Wednesday 4 October 2034 |
| 15 Aug 1990 | Sunday 31 December 2017 | Tuesday 9 September 2031 | Thursday 18 May 2045 |
| 1 Jan 2000 | Wednesday 19 May 2027 | Friday 25 January 2041 | Sunday 4 October 2054 |
| 1 Jan 2010 | Tuesday 19 May 2037 | Thursday 26 January 2051 | Saturday 4 October 2064 |
Someone born on 1 January 2000 reaches 10,000 days on 19 May 2027, roughly 27 years and 4 months in. The 20,000th day falls on 4 October 2054, about nine months after the 54th birthday, which is why it is a rarer milestone to notice.
Frequently Asked Questions (FAQs)
Enter your date of birth and press Calculate Age. The “Age on this date” field starts at today, so you get your age now; change it to any past or future date to see your age then. For example, someone born on 15 May 1990 is 36 years, 4 months and 18 days old on 3 October 2026, which is 13,290 days.
Yes, for most of the year. Someone born on 1 January and someone born on 31 December of the same year are both the same age for 364 days, and only one day apart in age overall.
The calculator adds whole calendar months to the birth date first, then counts the remaining days. If a month is shorter than the birth day (for example the 31st), the last day of that month is used.
In leap years your birthday falls on 29 February. In common years the calculator treats 1 March as the observed birthday, which is the convention used in many countries.
Press “Copy share link” under the result. The link contains the two dates, so anyone who opens it sees the same calculation ready to go.
Enter your date of birth and leave the Age on date as today. The calculator shows your current age in years, months and days, plus your total days lived and the countdown to your next birthday.
Enter your date of birth, then change the Age on date to the day you want to check, for example 1 September 2026 for a school cut-off or a future birthday. The result shows your exact age on that date in years, months and days.
Enter your date of birth and the date you want to check. Besides years, months and days, the result lists your total months, weeks, days and hours.
Yes. Set the "Age on" date to the event date instead of today, for example a wedding, retirement date or application deadline, and the result shows your exact age on that day.
The result includes a countdown in days to your next birthday, the age you will turn and the weekday it falls on.
Chronological age is simply the time since birth, which is what this calculator measures. Biological age is an estimate of how well the body is functioning compared with typical people of the same age, and it needs medical or lab measurements.
Count the days from your date of birth to today. For someone born on 1 January 2000, 9 November 2026 is 9,809 days later. The calculator shows this as “total days” under the years, months and days result.
Enter your date of birth and set the “age on” date to the past date. Someone born on 15 August 1990 was 19 years 4 months 17 days old on 1 January 2010.
In years that are not leap years the birthday is counted on 1 March, so the age goes up on that day. The next-birthday result follows the same rule.
Yes. Set the 'age on' date to any future day and the calculator returns the age in years, months and days on that date.
Age in years is the number of birthdays passed. Exact age adds the months and days since the last birthday, which is what some forms and eligibility checks ask for.
Confirm official deadlines. Results follow the calendar rules described on this page. Contracts, court time limits and official deadlines can count days differently, so confirm any legally important date against the governing document. See our full disclaimer.
Guides that use this calculator
- How to Calculate Your Exact Age on Any Date – Work out an exact age in years, months and days from a date of birth, on today’s date or any past or future date, including leap-day birthdays.