Age calculation is a crucial function in PHP development. It is used for various purposes, such as determining an individual's age, calculating the length of a membership, or determining the duration between two dates. The PHP Age Calculator is a widely used tool that allows developers to calculate age easily. In this tutorial, you will learn how to create a simple age calculator program using PHP. By the end of this tutorial, you will better understand how to use PHP to create a useful and practical age calculator program.

PHP Age Calculator Program Demo

This PHP code calculates a person's age based on their birth date and a specified date. It is a simple calculator program that receives a user input for the date of birth and the date to calculate the age and gives the result as output.

PHP Program to Calculate Age

    $DOB = $_POST['DOB'];
    $ToDate = $_POST['ToDate'];
    if (empty($DOB) || empty($ToDate)) {
        $Error = "Both input values are required.";
    } else {
        $bday = date_create_from_format('Y-m-d', $DOB);
        $today = date_create_from_format('Y-m-d', $ToDate);
        if (!$bday || !$today) {
            $Error = "Both input values must be a valid date.";
        } else {
            $DOB = $bday->format('d F Y');
            $ToDate = $today->format('d F Y');
            $age = date_diff(date_create($DOB), date_create($ToDate));
            $Result = "Birth Date: <strong>$DOB</strong><br>";
            $Result .= "Age <strong>{$age->y} Years, {$age->m} Months, {$age->d} Days</strong> as on <strong>{$ToDate}</strong>";

PHP Age Calculator – Understanding the Basics

The first step in developing a PHP Age Calculator is to understand the basics of the calculation process. Age is calculated based on the difference between the current date and the individual's birthdate. The process involves calculating the years, months, and days between the dates.

Developing the PHP Age Calculator

To develop an age calculator in PHP with a user interface, you can follow the steps below:

  1. Check for form submission: First, check whether the user has submitted the form using the $_SERVER["REQUEST_METHOD"] variable. Process the input if the form was submitted using the "POST" method.
  2. Validate input values: Check if the user has provided the date of birth and the specified date. If any of these fields are empty, set an error message. If both values are not empty, proceed to validate the date format.
  3. Validate date format: To validate the date format, use the date_create_from_format() function. If the input values are not valid dates, set an error message. If both dates are correct, format the dates and proceed to calculate the age.
  4. Calculate the age: To calculate the age, use the date_diff() function, which takes two Date objects as arguments and returns a DateInterval object representing the difference between the two dates.
  5. Display the result: To display the result, show the date of birth and age in years, months, and days with the specified date. If there is an error, display the error message.

Following the above steps, you can create an age calculator in PHP that validates input values and displays the result clearly and visually appealingly.


In conclusion, the PHP Age Calculator is an essential tool for developers who need to calculate age in their PHP projects. It is accurate, efficient, user-friendly, and customizable. Following the simple steps outlined in this article, you can quickly develop a PHP Age Calculator that meets your specific requirements.