How to Measure Script Execution Time in PHP?

Measuring the script execution time in PHP is the time required to execute the PHP script. To calculate script execution time use clock time rather than the CPU execution time. Measuring script execution time is useful to check and improve the execution time for better application performance.

Measuring Script Execution using microtime() Function

The most commonly used method to measure script execution time in PHP is the microtime() function. This function returns the current Unix timestamp in microseconds, which allows for precise timing of code execution.

Example: Measuring script execution time

Sample PHP Script

<?php

for($i = 1; $i <= 1000; $i++) {
    echo "Hello Geeks!";
} 
?>

First use the microtime() function before starts the script and at the end of the script. Then using formula (End_time - Start_time). The microtime() function returns time in seconds. Execution time is not fixed, it depends upon the processor.

<?php

// Starting Clock Time in Seconds
$start_time = microtime(true);
$a = 1;

// Start Loop
for($i = 1; $i <= 1000; $i++) {
    $a++;
} 

// End Clock Time in Seconds
$end_time = microtime(true);

// Calculate the Script Execution Time
$execution_time = ($end_time - $start_time);

echo "Script Execution Time = " . $execution_time . " sec";

?>

Script Execution Time = 2.1934509277344E-5 sec

Measuring Script Execution using hrtime() Function (High-Resolution Timer)

PHP 7.3 introduced the hrtime() function, which provides nanosecond-level precision for measuring execution time. This method is ideal for situations where microsecond precision isn't enough, and you need even more detailed performance data.

Example: Measuring script execution time with hrtime() function.

<?php

// Start Measuring Time
$start_time = hrtime(true);

// Example Script
for ($i = 0; $i < 1000000; $i++) {
    $x = sqrt($i);
}

// End Measuring Time
$end_time = hrtime(true);

// Calculate Execution time (in Nanoseconds)
$execution_time = $end_time - $start_time;

// Convert to Seconds (1 second = 1 billion nanoseconds)
$execution_time_in_seconds = $execution_time / 1e9;

echo "Execution time: " 
    . $execution_time_in_seconds . " seconds";

?>

Execution time: 0.020944947 seconds