microtime for seconds

Question

I’m checking how long a API delay to respond and I’m picking up the values at the beginning with microtime(true) and at the end with microtime(true) therefore;

$start = microtime(true);
...
...
...
...
$end = microtime(true);

To convert to seconds the current code divides the subtraction of the values by 60:

($end - $start) / 60

But I’ve done a lot of research and all I can find is to divide the value by 1000000, how do I get the difference of these values in segundos?