Quote from: mnyonpa on July 13, 2013, 07:15:06 AM

Could you please update the profit calculations for 21% and more difficulty growth?

Or maybe someone can recommend a good calculator that allows both to account for difficulty growth and delay in mining start?

http://www.bitcoinx.com/profit/ is a very good one

For estimated starting difficulty use the formula: X*(1+Z/100)^(Y/13)

where X is current difficulty
Z is % difficulty increase per cycle
Y is days till delivery

For profitability decline per year use: 1/[(1+Z/100)^(365/13)]

eg. for 21% increase and hardware arrival in 90 days

starting difficulty: 26mil * 1.21^(90/13) = 97907276
profitability decline per year: 1/[1.21^(265/13)] = 0.0047385

Plug those values into the calculator with your other info

Too easy

Keep in mind that a linear percentage increase in difficulty is very unlikely and so predictions of more than a few months or so will be inaccurate