Please don't invest in mining without first learning how to compute your expected return. Too many newbies blindly invest and end up losing money.
For example, on cex.io, a popular cloud mining site, 1 GH/s costs 0.074 BTC, but 1 GH/s will never mine more than 0.05 BTC. For every GH/s you buy on that site at that price, you will lose up to 0.024 BTC.
how do you calculate never mining more than .05 BTC? so investing in CEX results in losing up to .024 BTC? so invest, or no? it looks profitable atm!
When the difficulty rises, the revenue falls. The difficulty will be going up in a couple days so the return you are getting now will drop soon, and then again in 12 or so days, and so on...
To calculate the maximum, you estimate the future difficulty and add up the payments. With the difficulty going up so quickly you don't really have to predict very far into the future before the revenue drops close to zero.