I want to rent a rig for mining, I want to ask, whether to rent the rig will always lose?
and how to calculate the price of the rental cost of the rig with a good coin to us quarry?
http://www.bitcoinx.com/profit/
Go to the above site, enter the hashrate and multiply the number of days times the 24 hour earning number then subtract how much you will pay to rent the machine.
In my experience mining rentals will charge you much more then your expected profit.
If you can PPS mine somewhere then nicehash is a good site to use for mining rentals as they sometimes charge under what PPS pays based on difficulty