# Difficulties calculating mined ETH per month

I am trying to replicate calculator for ethereum mining available at

https://www.cryptocompare.com/mining/calculator/eth

So far I got to following formula

`Seconds in 1 month` / (`Total Hash Power MH/s` / `My Hash Power MH/s * Block Time s`) So in my case with following parameters:

Seconds per month: 2592000

Total Hash power MH/s: 30728202.35

My hash power MH/s: 74.525

Block Time s: 15

I get `0.4190912262` as a result opposed to `2.10` value from online calculator mentioned above. I'm not entirely sure where my formula is wrong i.e. I calculate seconds needed to mine 1 block and then divide whole month by these seconds to find out how many blocks I can mine.

For simplicity assume all other costs like electricity etc.. are 0

Let

``````A = blocksPerMonth
= nSecondsPerMonth / blockTime
= 2592000 / 15
= 172800

B = chanceOfWinning
= yourHashPower / totalHashPower
= 74.525 / 30728202.35
= 0.00000242529644758083
``````

The chance of winning a single block is then:

``````A * B = chanceOfWinningOneBlock
= 172800 * 0.00000242529644758083
= 0.419091226141968
``````

This is the number you calculated. You simply have to multiply that by 5 (which is the number of ether one wins if one wins the block) to get the number you're looking for.

``````(A * B) * 5 = expectedEtherPerMonth
= 0.419091226141968 * 5
= 2.09545613070984
``````
• Is 5 a constant or can it vary? – Ilja May 30 '17 at 8:43
• It's definitely a constant. It will take a hard fork to change it. – Thomas Jay Rush May 30 '17 at 10:33