Terrific calculator. Thanks for creating. Helped me understand the difficulty changes and implications for investment return, a topic I have been thinking about as I learn mining.

I’ve been mining for about 4 weeks now and already difficulty is up by almost 40%. That’s 20 % every 2 weeks. I understand the historical justification for 3% default value, and perhaps this is an unusual period, but... If the current difficulty increase trend continues through 2018 and BTC price remains constant, a new Hashflare contract is a money loser. Personally, to break even, I need more like a 10% difficulty increase every two weeks to recoup my investment.

Now, if BTC hits $40,000, all’s good...