How do I calculate a user's age given a date of birth?

Question

I need to calculate ages depended on birthday from a table of customers.

This is my code:

// customer age
function calculate_customer_age($startDate,$endDate){
    $endDate=date(m-d-y);
    $startDate= $customer['birthday'];
    $fromDate= new DateTime($startDate);
    $toDate= new DateTime($endDate);
    echo $fromDate->diff($toDate)->days;
}

In the last row, I need to echo age calculated depended on retrieve from a table of a customer from MySQL.

What happens when you run your code? Errors? Wrong result? Btw, you can remove the `$endDate` variable completely. If you just do `$toDate = new DateTime()` you will get the current date. — M. Eriksson, Aug 23 '18 at 11:03
Not sure if it's a typo, but `date(m-d-y)` should be `date('m-d-y')`. — GiamPy, Aug 23 '18 at 11:05
Possible duplicate of [Calculate age based on date of birth](https://stackoverflow.com/questions/19521146/calculate-age-based-on-date-of-birth) — Ronnie Oosting, Aug 23 '18 at 11:12

score 0 · Answer 1 · answered Aug 23 '18 at 11:09

You can use below code in your function, which will calculate age upto today. You can modify $today to use the end date and format you want.

$dateOfBirth = $customer['birthday'];
$today = date("Y-m-d");
$diff = date_diff(date_create($dateOfBirth), date_create($today));
echo 'Age is '.$diff->format('%y');

score 0 · Answer 2 · edited Aug 23 '18 at 11:15

You had several errors in your calculate_customer_age function, instead you can use the below code to get the difference in days between two dates:

function calculate_customer_age($startDate, $endDate)
{
    $startDate = DateTime::createFromFormat("m/d/Y", $startDate);
    $endDate = DateTime::createFromFormat("m/d/Y", $endDate);
    return $startDate->diff($endDate)->days;
}

echo calculate_customer_age("11/30/2008", "08/23/2018"); // 3553

Documentation:

http://php.net/manual/en/class.datetime.php

score 0 · Answer 3 · answered Aug 23 '18 at 11:13

There are many errors in your code. There is no need to pass end date in your function. You can use the following code to get the age.

function calculate_customer_age($startDate){
    $fromDate = new DateTime($startDate);
    $toDate       = new DateTime('today');
    return $fromDate->diff($toDate)->days;
       // or return $fromDate->diff($toDate)->y;
}

echo calculate_customer_age($customer['birthday']);

score 0 · Answer 4 · answered Aug 23 '18 at 11:18

PHP >= 5.3.0

object oriented

$from = new DateTime('1970-02-01');
$to   = new DateTime('today');
echo $from->date_diff($to)->y;

procedural

echo date_diff(date_create('1970-02-01'), date_create('today'))->y;

MySQL >= 5.0.0

SELECT TIMESTAMPDIFF(YEAR, '1970-02-01', CURDATE()) AS age

score 0 · Answer 5 · answered Aug 23 '18 at 11:20

If you want to calculate customer's age in days, you should do so:

function calculate_customer_age($startDate){
        $fromDate= new DateTime($startDate);
        $toDate= new DateTime();
        $difference = $fromDate->diff($toDate)->days;
        return $difference->format('%a');
}

score 0 · Answer 6 · answered Aug 23 '18 at 11:23

php code

$startDate = '05-01-1988'; // sample start date or dob
$end_Date = '23-08-2018'; // smmple end date

echo calculate_customer_age( $startDate , $end_Date );

php function that returns age -

function calculate_customer_age( $startDate , $endDate ) //function returns age   
{   
    $diff = date_diff( date_create( $startDate  ), date_create( $endDate ) );
    return $diff->format('%y Years, %m Months, %d Days');
}

Sample Output :

30 Years, 7 Months, 18 Days

How do I calculate a user's age given a date of birth?

6 Answers6

object oriented

procedural