PHP - Get the last day of the month of a specific date

By xngo on August 4, 2019

In PHP, you can get the last day of the month of a specific date by using the t format option of the date() function. Here are some examples.

Object oriented way

<?php
$dt = new DateTime();       // Create an instance of the current date & time.
$dt->setDate(2019, 8, 4);   // Set $dt to a different date.
echo $dt->format('Y-m-t');  // Output: 2019-08-31
 
echo "\n";
 
// Or, you can also use modify(). It uses the same format as strtotime().
$dt->modify('last day of this month');
echo $dt->format('Y-m-d');  // Output: 2019-08-31
?>

Output

2019-08-31
2019-08-31

Functional way

If you prefer to use functions, then use mktime() to set your date and then use date() to get the last day of the month.

<?php
$year   = 2019;
$month  = 8;
$day    = 4;
$last_day_of_month = date("Y-m-t", mktime(0,0,0,$month,$day,$year));
 
echo $last_day_of_month;  // Output: 2019-08-31
?>

Output

2019-08-31
PHP

About the author

Xuan Ngo is the founder of OpenWritings.net. He currently lives in Montreal, Canada. He loves to write about programming and open source subjects.