Measuring Script Execution Time in PHP

In PHP, measuring script execution time is crucial for performance optimization and debugging. PHP provides several builtin functions to measure how long your code takes to execute, each with different levels of precision.

Using microtime() Function

The most commonly used method for measuring execution time with microsecond precision ?

<?php
// Start the timer
$start = microtime(true);

// Simulate some work
for ($i = 0; $i < 1000000; $i++) {
    $dummy = sqrt($i);
}

// End the timer
$end = microtime(true);

// Calculate the execution time
$executionTime = $end - $start;

// Output the result
echo "Script execution time: " . number_format($executionTime, 6) . " seconds";
?>

Script execution time: 0.045123 seconds

Using time() Function

For basic timing with secondlevel precision ?

<?php
// Start the timer
$start = time();

// Simulate some work
sleep(2);

// End the timer
$end = time();

// Calculate the execution time
$executionTime = $end - $start;

// Output the result
echo "Script execution time: " . $executionTime . " seconds";
?>

Script execution time: 2 seconds

Using hrtime() Function (PHP 7.3+)

The most precise method available, providing nanosecond accuracy ?

<?php
// Start the timer
$start = hrtime(true);

// Simulate some work
for ($i = 0; $i < 500000; $i++) {
    $dummy = $i * $i;
}

// End the timer
$end = hrtime(true);

// Calculate the execution time in seconds
$executionTime = ($end - $start) / 1e9;

// Output the result
echo "Script execution time: " . number_format($executionTime, 9) . " seconds";
?>

Script execution time: 0.012345678 seconds

Measuring Time and Memory Usage

Combine timing with memory usage monitoring for comprehensive performance analysis ?

<?php
// Start measurements
$start = microtime(true);
$startMemory = memory_get_usage();

// Create a large array to demonstrate memory usage
$largeArray = array();
for ($i = 0; $i < 10000; $i++) {
    $largeArray[] = str_repeat('x', 100);
}

// End measurements
$end = microtime(true);
$endMemory = memory_get_usage();

// Calculate results
$executionTime = $end - $start;
$memoryUsed = $endMemory - $startMemory;

// Output results
echo "Execution time: " . number_format($executionTime, 4) . " seconds<br>";
echo "Memory used: " . number_format($memoryUsed / 1024, 2) . " KB";
?>

Execution time: 0.0123 seconds
Memory used: 976.56 KB

Comparison

Conclusion

Use microtime(true) for most timing needs, hrtime(true) for highprecision requirements, and combine with memory functions for comprehensive performance analysis. Choose the method based on your precision requirements and PHP version compatibility.