User blog comment:V3hemenc3/What is the accepted number of farm on an AD carry?/@comment-655312-20120921165815

There's no right number. If you watch the pros, there are games when the best farmer has 200 creeps at 30', and others where they may have 400 (though the latter is rather rare).

If you want something to aim for, I'd say around as many minutes as have passed x 10, so 100 at 10, 200 at 20, 300 at 30 and so on, but it would be unnatural to achieve this casually game after game, because of the inevitable events precluding your farm (ganks from both sides, roaming opportunities, priority objectives such as golem, lizard, dragon and baron contests, trades with enemy champions rendering you too weak to stay in lane, etc.).

What's more important is you assess every situation and make the right choice - you see your team racing to kill the dragon, but you have a wave of 15 minions in your lane approaching your turret - should you help them, or stay and rack up some gold for yourself? You've just killed both of your opponents in bottom lane, but the minions are still in the middle - should you push and score some extra money, or pop over to mid lane and try take out the carry there?

Also, turrets shouldn't be underestimated - people take the gold they provide for granted sometimes, but there is no guarantee you'll be able to take down all or any of an enemy team's turrets in good time.

Lastly, see how the enemy carry is doing, I find that's usually the most objective measure of performance. Do your best and keep improving and you'll be fine.