You can use rand() together with pow() to make this happen: $digits = 3; echo rand(pow(10, $digits-1), pow(10, $digits)-1); Save This will output a number between 100 and 999. This because 10^2 = 100 and 10^3 = 1000 and then you need to subtract it with one to get it in the desired range. If 005 also is a valid example you'd use the following code to pad it with leading zeros: $digits = 3; echo str_pad(rand(0, pow(10, $digits)-1), $digits, '0', STR_PAD_LEFT); Save Share Improve this answer Follow