modify() : Modifying date object to add or subtract date and time parameters in PHP

Modify a date with relative text

modify() applies a relative date/time expression such as +2 days or next Monday. With DateTime the object changes; with DateTimeImmutable a new object is returned.

$date = new DateTimeImmutable('2026-09-14 10:00:00');
$changed = $date->modify('+2 days 3 hours');
echo $changed->format('Y-m-d H:i:s');

In PHP 8.3+, malformed modification strings throw DateMalformedStringException, so validate or catch exceptions when the expression comes from outside your code.

This is another way to add or subtract a date object with different month , days ,year , hour , minutes , sec etc.

PHP 8.3+ note: the object-oriented DateTime::modify() and DateTimeImmutable::modify() methods throw DateMalformedStringException for an invalid modifier string. Validate or catch exceptions when modifiers come from outside your code.

Here is an example on how to use modify function.

<?php
date_default_timezone_set ("Asia/Kolkata");
$date1=new DateTime("now") ; // current date
echo $date1->format('d-m-Y');
echo "<br>";
$date2=$date1->modify('+5 day');
 echo $date2->format('d-m-Y');
?>

The output is here

20-10-2026
25-10-2026

We can change the highlighted line like this

$date2=$date1->modify('+3 month +5 day -1 year ');

Output of this change is here

20-10-2026
25-01-2026

Including Time

<?php
date_default_timezone_set ("Asia/Kolkata");
$date1=new DateTime("now") ;
echo $date1->format('d-m-Y H:i:s');
echo "<br>";
$date2=$date1->modify('+5 day +6 hours +20 minutes +30 seconds ');
echo $date2->format('d-m-Y H:i:s');
?>

Output is here ( based on today's date and time). Refresh this page and check the changes in time.

20-10-2026 10:37:21
25-10-2026 16:57:51

Using fixed date and leap year

$date = new DateTime('2024-02-29 12:00:00');
$date2=$date->modify('+1 year +5 hours');
echo $date2->format('d-m-Y H:i:s');

Output is here

01-03-2025 17:00:00

PHP Date Functions Timestamp in PHP Displaying calendar for selection of date by user

Subhendu Mohapatra

Author & Instructor at plus2net

I write and maintain practical tutorials on Python, PHP, SQL, JavaScript, HTML, jQuery, and web development at plus2net. The tutorials focus on clear explanations, working examples, and code that readers can test and adapt while learning.

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modify() : Date modify

Modify a date with relative text

Including Time

Using fixed date and leap year

Subhendu Mohapatra