# Age calculator

URL: https://shahid09.is-a.dev/tools/age-calculator/
Author: Muhammad Shahid (https://shahid09.is-a.dev/)
Free tool · runs in your browser

Enter a date of birth to find an exact age in years, months and days, on today or any other date.

**Quick answer:** Enter a date of birth and the calculator shows the exact age in years, months and days, plus total months, weeks, days and hours, the weekday of birth and the days until the next birthday. It uses today by default; change the second date to find an age on a past or future date, such as a form deadline.

## How to use it

1. **Enter the date of birth.** Use the date picker or type the date.
2. **Check the second date.** It starts on today. Change it to find the age on another date.
3. **Read the results.** Exact age first, then totals and the next birthday.

## Example

Someone born on 15 January 2000, on 3 November 2026:

Input:

```
Date of birth: 2000-01-15
Age on: 2026-11-03
```

Output:

```
26 years, 9 months and 19 days
Total days: 9,789
Born on a: Saturday
Days to next birthday: 73
```

## Common errors and how to fix them

- **The date of birth is after the other date**: Age cannot be negative. Check the year in both dates.
- **No result appears**: Both dates are needed. Check that the date picker shows a full date.

## Frequently asked questions

### How is age calculated?

By counting completed years, then completed months, then the remaining days from the date of birth to the chosen date.

### What if I was born on 29 February?

In a non-leap year this calculator treats 28 February as your birthday for counting. Laws differ on whether 28 February or 1 March applies, so check when it matters legally.

### How do I work out my age on a specific date?

Change "Age on this date". Application forms and exams often ask for age on a fixed cut-off date.

### Why do some countries count age differently?

Traditional East Asian systems count a newborn as one. South Korea legally moved to international age in 2023 for most purposes. This tool uses the international method, starting at zero.

### How many days old am I?

See "Total days". Multiply by 24 for hours, which is also shown.

### What day of the week was I born?

See "Born on a". It uses the modern (Gregorian) calendar.

### Why might the month and day count differ from another site?

Months have different lengths, so methods differ by a day or so around month ends. Total days is always exact.

### Is my date of birth stored?

No. It is calculated in your browser, and it is gone when you leave the page.

### How do I calculate age in months for a baby?

See "Total months", which counts completed months since birth. For the gap between any two other dates, use the [date difference calculator](https://shahid09.is-a.dev/tools/date-difference-calculator/).

### Can I find how old someone was on a past date?

Yes. Set "Age on this date" to that past date, and the result is worked out for that day.

## Related

- [Date difference calculator](https://shahid09.is-a.dev/tools/date-difference-calculator/)
- [Time calculator](https://shahid09.is-a.dev/tools/time-calculator/)
- [Unix timestamp converter](https://shahid09.is-a.dev/tools/unix-timestamp-converter/)

## Sources

- [Wikipedia: Leap year](https://en.wikipedia.org/wiki/Leap_year)