They can mine about .185 btc left with .08 cents electricity in China.
.08 btc with .16 electricity like most of USA.
.01 btc with .30 electricity like alot of Europe.
even mining.thegenesisblock gives better numbers:
$220 in revenue in 3 mo with ~$90 in expenses
after that-pencil mod and another month of profitability.
total profit $145 or 0.228 BTC
assumed $0.12/kwh in electricity (this is what i pay in US) and $634/BTC
Your .12 electricity and 634 btc price will mine .129 btc lifetime.
Is your calculator adjusting for difficulty jumps every 2 weeks, which means less mining power.
In September when diff is near 38 Billion it will mine only .013 more btc.
Its the same numbers/formula . Only adjusted values. Change for diff, electricity, btc price. hash rate, power
I use 18% diff, .16 elec, current btc
And I did a whole article recently in which US customers have usually higher electricity rates than the wholesale cost on their bills. Typically including delivery, transportation, generation, and administrative fees this usually adds 4-6 cents to a bill. My wholesale rate here in PA is .12 cents but the bottom line is .16 when its all calculated and time to pay for the watts used.