# How old am I from my DOB?

Works out an exact age in years, months, and days from a date of birth (DOB), on today or any date, with the total days and the next birthday.

- Page: https://www.acalculator.org/days/dob-calculator
- JSON spec: https://www.acalculator.org/days/dob-calculator.json
- Version: c00d50094740

## Default answer

Example with the default inputs (Date of birth February 2, 2002, Age on October 5, 2026) on the example date Monday, October 5, 2026: You: 24 years, 8 months, 3 days old on October 5, 2026.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| birth | Date of birth | The day the person was born. |
| on | Age on | The date to work out the age on. Today, unless you change it. |
| name | Name | A name to use in the answer, for example your child’s name. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| age | Age | Whole years, then whole months, then days from the date of birth to the age-on date. |
| who | Who | The name you entered, or “You”. |
| years | Age in years | Completed years (birthdays passed). |
| months | Total months | Completed months since birth. |
| weeks | Total weeks | The total days as whole weeks and days. |
| days | Total days | Days from the date of birth to the age-on date. |
| bornOn | Born on a | The weekday of the date of birth. |
| next | Next birthday | The first birthday after the age-on date. A February 29 birthday is February 28 in other years. |
| daysToNext | Days to next birthday | Days from the age-on date to the next birthday. |
| turns | Turns | The age in years on the next birthday. |

## Method

Count whole years from the date of birth while the birthday is on or before the age-on date, then whole months the same way, then the days left.

## Assumptions

- A month is counted when the same day of the month is reached; when that month is shorter, its last day counts (January 31 plus one month is February 28, or 29 in a leap year).
- A February 29 birthday falls on February 28 in common years.
- Total days count from the date of birth up to the age-on date, the birth day itself not included, so a baby is 1 day old the day after birth.
- Dates are calendar days with no time of day or time zone, so daylight-saving changes cannot add or lose a day.
- A date of birth after the age-on date gives no answer.

## Worked examples

1. birth = 1990-01-15, on = 2024-12-31 gives age = {"years":34,"months":11,"days":16}, years = 34, months = 419, days = 12,769, next = 2025-01-15, daysToNext = 15, turns = 35. Source: U.S. Naval Observatory, Leap Years: the Gregorian leap year rule. https://aa.usno.navy.mil/faq/leap_years.
2. birth = 2000-03-01, on = 2024-02-28 gives age = {"years":23,"months":11,"days":27}, days = 8,764, next = 2024-03-01, daysToNext = 2. Source: U.S. Naval Observatory, Leap Years: the Gregorian leap year rule. https://aa.usno.navy.mil/faq/leap_years.
3. birth = 2000-02-29, on = 2026-02-28 gives age = {"years":26,"months":0,"days":0}, days = 9,496, bornOn = Tuesday, next = 2027-02-28, daysToNext = 365, turns = 27. Source: U.S. Naval Observatory, Leap Years: the Gregorian leap year rule. https://aa.usno.navy.mil/faq/leap_years.
4. birth = 2002-02-02, on = 2026-09-27, name = Pat gives age = {"years":24,"months":7,"days":25}, who = Pat, weeks = {"weeks":1286,"days":1}, days = 9,003, bornOn = Saturday, next = 2027-02-02, daysToNext = 128. Source: U.S. Naval Observatory, Leap Years: the Gregorian leap year rule. https://aa.usno.navy.mil/faq/leap_years.

## FAQ

### How do I calculate my age from my date of birth (DOB)?

Use our DOB calculator above to find your exact age from your date of birth. Simply enter your date of birth (DOB) and the date you want to calculate your age as of. The calculator will show your precise age in years, months, and days. For example, if your DOB is January 15, 1990 and you want to know your age on December 31, 2024, you would be 34 years, 11 months, and 16 days old.

### What is a DOB calculator and how does it work?

A DOB calculator (Date of Birth calculator) is a tool that calculates your exact age based on your birth date. Our calculator uses precise date arithmetic to determine the exact number of years, months, and days between your date of birth and any specified end date. It accounts for leap years and varying month lengths.

### How accurate is this DOB age calculator?

Our DOB calculator accounts for leap years (including century rules), varying month lengths (28, 29, 30, or 31 days), and precise day counting. It counts whole calendar days with no time of day or time zone, so the answer is exact to the day. Where a law or form sets its own rule for counting age, follow that rule.

### Can I calculate age for someone else using their DOB?

Yes, you can calculate the age of anyone by entering their date of birth (DOB) and the date you want to know their age as of. You can also add their name to the answer. This is useful for parents tracking their children's ages, HR departments calculating employee ages, or anyone needing to determine someone's age for legal or administrative purposes.

### What can I use this DOB calculator for?

This DOB calculator is perfect for calculating your current age, finding your age on a specific date in the past or future, determining eligibility for age-restricted activities, planning for milestone birthdays, and verifying age for various applications. To compare two people, use the age difference calculator.

### How does the calculator handle leap years and February 29th birthdays?

The calculator accounts for the extra day (February 29) in leap years. A February 29 birthday falls on February 28 in other years, so someone born on February 29, 2000 is exactly 26 on February 28, 2026. If you were born on March 1, 2000, and want to know your age on February 28, 2024, you would be 23 years, 11 months, and 27 days old.

### Can I calculate my age on a future date?

Yes, you can enter any future date as the end date to see what your age will be on that date. For example, if you want to know your age on your next birthday, simply enter your date of birth and the date of your upcoming birthday. This is useful for planning milestone celebrations or understanding age requirements for future events.

### What's the difference between DOB calculator and other age calculators?

A DOB calculator specifically focuses on calculating age from your date of birth, making it ideal for people searching for 'dob calculator' or 'birth date calculator'. While other age calculators might focus on different aspects like chronological age or age differences, our DOB calculator provides the same accurate calculations with terminology optimized for DOB-related searches.

## Sources

- U.S. Naval Observatory, Leap Years: the Gregorian leap year rule. https://aa.usno.navy.mil/faq/leap_years