Solution is based on the array_search() function. You need to use PHP 5.5.0 or higher. $userdb=Array ( (0) => Array ( (uid) => '100', (name) => 'Sandra Shush', (url) => 'urlof100' ), (1) => Array ( (uid) => '5465', (name) => 'Stefanie Mcmohn', (pic_square) => 'urlof100' ), (2) => Array ( (uid) => '40489', (name) => 'Michael', (pic_square) => 'urlof40489' ) ); Solution-1: function myfunction($products, $field, $value) { foreach($products as $key => $product) { if ( $product[$field] === $value ) return $key; } return false; } Solution-2: $key = array_search(40489, array_column($userdb, 'uid')); echo ("The key is: ".$key); //This will output- The key is: 2 The function array_search() has two arguments. The first one is the value that yo