Hi, not only to you. I have a HD6870 an hashrate ah ~300. On the site it is shown somehow ~220, to ~350. I think it is normal. The site is calculating somewhere in the middle.
Thanks for your reply. I recognized that calulations are correct. But 'supervising' a bunch of small miners by the provided live stats (my account -> workers seems) not really praticable.
Is there any kind of workaround? Haven't had a closer look at cgminer api but perhaps the bitminter api works better?