Age calculator
The age calculator works out your exact age from a date of birth as of today – how many years old you are, how many total months, and how many total days you have been alive. Handy for forms, anniversaries and simple curiosity. Everything runs entirely in your browser; no date is ever sent anywhere.
How the age calculator works
The tool compares the date of birth you enter with today's date taken from your device clock. Age in years is counted by the calendar: it subtracts the years and then checks whether your birthday has already occurred this year. If the current month and day have not yet reached your birth date, one year is subtracted – that is why the day before your birthday shows one year less than the day after.
Alongside years, the tool shows two extra views. Total months is the number of whole calendar months since birth (years × 12 plus the remaining months). Total days is the plain count of calendar days elapsed between the two dates, leap years included, so you never have to account for them by hand.
How to use the age calculator
- Click the Date of birth field and pick the day, month and year.
- Results appear instantly – there is nothing to confirm.
- Read the three tiles: years, total months and total days.
- Change the date anytime and the values recalculate.
Example for a date of birth of 15 March 1990 as of today (11 July 2026):
| Metric | Value |
|---|---|
| Age in years | 36 |
| Total months | 435 |
| Total days | 13,267 |
Note: the exact day count depends on the current date when you open the tool.
What the age calculator is good for
Most often it helps when filling in forms and applications that ask for an exact age, or when checking age conditions (school entry, retirement age, contract age limits). Parents can easily work out a child's age in months, which is useful for pediatric charts and developmental milestones.
It also works well for anniversaries and celebrations – you can see how many days remain until a round date or which day of your life you are living right now. Because total days is calculated too, you can plan symbolic milestones such as your 10,000th day.
Everything happens locally in your browser: your date of birth, which is sensitive personal data, is never sent or stored. The tool works offline and requires no sign-up.
FAQ
Does the calculator handle leap years correctly?
Yes. The day count is the actual difference between two calendar dates, so leap years and the 29-day February are included automatically without any manual adjustment.
Which date is used as "today"?
The system date and time of your device. If the date on your computer or phone is set incorrectly, it will also affect the result – check your clock settings.
Why does the day before my birthday show one year less?
Age in years only increases on your birthday. Until the birthday occurs in the current year, the tool subtracts one year to match how age is normally understood.
What does "total months" mean?
It is the total number of completed calendar months since birth, that is years multiplied by twelve plus the remaining whole months. For children it is a practical figure for pediatric charts.
Can I enter a future date?
You can, but the results will not make sense (age comes out negative or zero). The tool is meant for dates of birth in the past.
Is my date of birth sent to a server?
No. The whole calculation runs in your browser using JavaScript. The date is never sent, stored or shared – once you close the page, no trace remains.
Does the tool count hours and minutes?
No, it works to day precision. Only the date of birth is entered, not a time, so the smallest unit of the result is one day.
Is the result legally binding?
It is a guideline aid for a quick calculation. For official purposes, always rely on official documents and the precise definition of age under the relevant regulation.
📅 Last updated: 11 July 2026