Where do you mine?
I'm mining at blocksolved.com at the moment but my daily earning is lower than I have expected.
570 kh/s = 300k/day @blocksolved.com (= 12,5k/hour)
and only 200k/day @nut2pools.com (= 8,5k/hour)

When I calculate my estimated earnings with a calculator at the current block reward and current diff I should get about 500k (~ 20k/hour) and compared with your earnings at least 1/4, so 17,5k/hour.
How can this differ so widely?

BTW my hashrate is always shown 30-50% lower on the pool dashboard  than in my miner. Haven't seen more than 450kh/s on the dashboard for 2 days, mostly it shows about 250kh/s.