How to calculate how much can you mine cryptocurrencies with your CPU?

In the following few steps you will learn how to calculate the required system and hash power to mine a specified amount of cryptocurrency. In this post I've used #Monero as an example.

1. First of all you have find out how much time does it take for a block?
   For example #Monero currently has an average block time of 2 minutes (average block time = avgBlkTime).
   Let's do simple math:
   1 d (day) = 24 h (hours) = 24*60 minutes = 1440 min (minutes)
   Therefore there are approximately:
   1440/2 = 720 blocks/day (blocks per day)
   blocks a day.

2. The reward you get for mining is proportional to the share of the network hashrate you got (hashrate = hsRt). Currently the hashrate for example for #Monero is:
   approx. 23.0 MH/s = 23000000 H/s (for more info. check http://moneroblocks.info/)

3. An important parameter to consider in your calculations is that the amounts of rewards decrease in each block with time. Now for the sake of our calculations we will use 9 XMR for the reward (average block reward = avgBlkRwd).
   (To find out the exact reward at any given time, you could go to a block explorer such as http://moneroblocks.info/ for #Monero and click on the most recent block and write down the reward for that block.)

4. For the final step of the calculations to calculate the reward you want on a daily basis (daily reward = dRwd):
   dRwd = (1440/avgBlkTime) * avgBlkRwd * n/(hsRt)
   where your share of the hashrate is "n". You can calculate with the following relation:

   ---------------------------------------------------------------------------
                n = dRwd*hsRt/( (1440/avgBlkTime)*avgBlkRwd )      
   ---------------------------------------------------------------------------
   

Now for example you want to mine 0.5 XMR from a #Monero mining pool then you have to have a system with a hashrate of:

dRwd = 0.5 XMR
hsRt = 23000000 H / s
avgBlkTime = 2 min
avgBlkRwd = 9 XMR

n = 0.5 * 23000000 / (720 * 9) = 1774.6914 H/s