Where Do I get the Right Code for my ECO

Hello,
Can someone tell me where I can go to the code for an ECO? I want to insert the first few moves and come up with a proper ECO code. I tried http://www.chesslab.com but it just says Benko's Opening. If I start up a game in its database, it says C20 King's Pawn Game.
Game # Game 6473283 is the game I want to find a proper ECO code for.

kop

Click on the game link you posted.
Scroll down and you see;

Opening A00 Benko's Opening.

The problem with the (popular) g3 opening is that is was not given a specific code when the Encyclopaedia of Chess Openings was written. Instead it was grouped with the irregular flank openings which are all A00. Most g3 games will transpose to openings with another code, in your game it transposed to C20. Since your first move was g3 the code is A00, but had you switch around your first 2 moves the correct code would have been C20.

365Chess.com will give you the correct codes for openings.