How to Find Difference Between Two Dates in PHP: Methods Compared

In PHP, you can find the difference between two dates using the DateTime class with its diff() method, which returns a DateInterval object showing the difference. Alternatively, you can use strtotime() to convert dates to timestamps and subtract them to get the difference in seconds.

Quick Comparison

Here is a quick comparison of the two common ways to find date differences in PHP.

Aspect	DateTime::diff()	strtotime() subtraction
Type of result	DateInterval object with detailed parts	Integer (seconds)
Precision	Days, months, years, hours, minutes, seconds	Seconds only
Ease of use	More readable and object-oriented	Simple arithmetic with timestamps
Handling invalid dates	Throws exceptions or errors	Returns false or incorrect results
Best for	Detailed date differences	Quick time interval calculations
Requires PHP version	PHP 5.3+ (modern PHP)	Any PHP version

Key Differences

The DateTime class in PHP provides a powerful and clear way to calculate the difference between two dates. Using the diff() method, it returns a DateInterval object that breaks down the difference into years, months, days, hours, minutes, and seconds. This makes it easy to understand and format the difference in a human-friendly way.

On the other hand, using strtotime() converts date strings into Unix timestamps (seconds since 1970-01-01). Subtracting these timestamps gives the difference in seconds, which you can then convert manually into days or other units. This method is simpler but less descriptive and requires extra steps to format the output.

Also, DateTime handles invalid or complex date formats more gracefully and supports time zones, while strtotime() can fail silently or return unexpected results if the date format is not recognized.

Code Comparison

Here is how you find the difference between two dates using the DateTime class and its diff() method in PHP.

php

<?php
$date1 = new DateTime('2024-01-01');
$date2 = new DateTime('2024-04-15');
$diff = $date1->diff($date2);
echo "Difference: {$diff->y} years, {$diff->m} months, and {$diff->d} days.";
?>

Output

Difference: 0 years, 3 months, and 14 days.

strtotime() Equivalent

This example shows how to find the difference between two dates by converting them to timestamps with strtotime() and subtracting.

php

<?php
$date1 = '2024-01-01';
$date2 = '2024-04-15';
$diffSeconds = strtotime($date2) - strtotime($date1);
$diffDays = $diffSeconds / (60 * 60 * 24);
echo "Difference: {$diffDays} days.";
?>

Output

Difference: 105 days.

When to Use Which

Choose DateTime::diff() when you need a detailed, human-readable difference between dates, including years, months, and days. It is best for applications like age calculation, event countdowns, or any case where date parts matter.

Use strtotime() subtraction when you only need a quick difference in seconds or days and want a simple, fast calculation without extra formatting. This is suitable for measuring elapsed time or intervals where precision to the second is enough.

Key Takeaways

Use DateTime::diff() for detailed and readable date differences.

Use strtotime() subtraction for quick, simple time interval calculations.

DateTime handles complex dates and time zones better than strtotime().

The DateInterval object from diff() provides years, months, days, and more.

Subtracting timestamps gives difference in seconds, which you can convert to other units.