microtime to seconds

microtime.php

<?php
function format_period($seconds_input)
{
    $hours = (int)($minutes = (int)($seconds = (int)($milliseconds = (int)($seconds_input * 1000)) / 1000) / 60) / 60;

    return $hours . ':' . ($minutes % 60) . ':' . ($seconds % 60) . (($milliseconds === 0) ? '' : '.' . rtrim(
                $milliseconds % 1000,
                '0'
            ));
}

$startTime = microtime(true);
//whatever happens in between
echo '<br/>Total execution time in seconds: ' . format_period((microtime(true) - $startTime));