Accurate way to measure execution times of php scripts

You can use the microtime function for this. From the documentation:

microtime — Return current Unix timestamp with microseconds

---

If get_as_float is set to TRUE, then microtime() returns a float, which represents the current time in seconds since the Unix epoch accurate to the nearest microsecond.

Example usage:

$start = microtime(true);
while (...) {

}
$time_elapsed_secs = microtime(true) - $start;

You can use microtime(true) with following manners:

Put this at the start of your php file:

//place this before any script you want to calculate time
$time_start = microtime(true);

// your script code goes here

// do something

Put this at the end of your php file:

// Display Script End time
$time_end = microtime(true);

//dividing with 60 will give the execution time in minutes other wise seconds
$execution_time = ($time_end - $time_start)/60;

//execution time of the script
echo '<b>Total Execution Time:</b> '.$execution_time.' Mins';

It will output you result in minutes.

You can use REQUEST_TIME from the $_SERVER superglobal array. From the documentation:

REQUEST_TIME
The timestamp of the start of the request. (Available since PHP 5.1.0.)

REQUEST_TIME_FLOAT
The timestamp of the start of the request, with microsecond precision. (Available since PHP 5.4.0.)

This way you don't need to save a timestamp at the beginning of your script. You can simply do:

<?php
// Do stuff
usleep(mt_rand(100, 10000));

// At the end of your script
$time = microtime(true) - $_SERVER["REQUEST_TIME_FLOAT"];

echo "Did stuff in $time seconds\n";
?>

Here, $time would contain the time elapsed since the start of the script in seconds, with microseconds precision (eg. 1.341 for 1 second and 341 microseconds)

More info:

PHP documentation: $_SERVER variables and microtime function

Create file loadtime.php

<?php
class loadTime{
    private $time_start     =   0;
    private $time_end       =   0;
    private $time           =   0;
    public function __construct(){
        $this->time_start= microtime(true);
    }
    public function __destruct(){
        $this->time_end = microtime(true);
        $this->time = $this->time_end - $this->time_start;
        echo "Loaded in $this->time seconds\n";
    }
}

Than in the beggining of your script, after <?php write include 'loadtime.php'; $loadtime=new loadTime();

When page is loaded at the end there will be written "Loaded in x seconds"