I'm more interested in a calculator that is based on the difficulty instead of network hashrate and block time since low blocktimes are not particularily accurate.
That makes sense. Can you provide a sample calculation based on difficulty values?
http://alpha61.com/ethereum.jsonI use
2^32 * diff_coin / my_hashrate * 1e6 / 60 / 60 to get my block finding frequency based on diff for other coins (that are not quark) but that doesn't seem to be applicable for Ethereum.