How to find average from array in php?

first you need to remove empty values, otherwise average will be not accurate.

so

$a = array_filter($a);
$average = array_sum($a)/count($a);
echo $average;

DEMO

More concise and recommended way

$a = array_filter($a);
if(count($a)) {
    echo $average = array_sum($a)/count($a);
}

See here

The accepted answer works for the example values, but in general simply using array_filter($a) is probably not a good idea, because it will filter out any actual zero values as well as zero length strings.

Even '0' evaluates to false, so you should use a filter that explicitly excludes zero length strings.

$a = array_filter($a, function($x) { return $x !== ''; });
$average = array_sum($a) / count($a);