A snippet that will calculate the work/cost factor of encrypting. Based on a number in seconds it suggest a cost factor

calculate-encryption-time.php

/**
 * This code will benchmark your server to determine how high of a "cost" you
 * can afford. You want to set the highest cost that you can without slowing
 * down your server too much. 10 is a good baseline, and more is good if your
 * servers are fast enough.
 * 
 * Obviously You should run this on the server that will be encrypting..
 */

// What is the maximum time, your server should spend on encrypting?
// Fractional number in seconds.
$timeTarget = 0.7;

// Calculating below here
$cost = 5;
do {
    $cost++;
    $start = microtime(true);
    password_hash("test", PASSWORD_BCRYPT, ["cost" => $cost]);
    $end = microtime(true);
} while (($end - $start) < $timeTarget);

echo "Appropriate Cost Found: " . $cost . "\n";