# Calculate Mining Time of a Block for a Given Hash Rate

In my laptop i've a graphic card that has more or less 10Mh/s rate for ethereum (Nvidia Geforce GTX 950M)

From the following link i've found a formula that gives me a 1.57 day for find a block.

Instead from the tool from etherscan.io I get a result of more o less 345 days.

Which is the right formula to extimate the time for me to find a block?

If can be usefull, I will use geth

## 2 Answers

I'm not sure how you got 1.57 days :)

• Current network hash rate is 19678.50 GH/s, or 19678500000000 H/s.
• Your current hash rate is 10 MH/s, or 10000000 H/s.
• Block time is ~14.91 seconds.

Plugging these into the calculation:

``````network hashrate / personalrate * blocktime         = time to find a block
(19678.5 GH/s / 10 MH/s * 14.91 s)                  = 29340643.5 seconds

(19678500000000 H/s / 10000000 H/s * 14.91 s) / (24h * 60m * 60s) = 339.6 days
``````

So ~340 days, equivalent to Etherscan's 345 days.

• due to a mistyping error in my excel file i've used, the formula gives me a wrong result – user2548436 Apr 24 '17 at 14:03
• This equation does not make sense. If you make the block time smaller, you should expect a smaller number of days to find a block. In this equation if i make block time smaller then it actually increases the number of days to find a block. That does not make sense – g00dnatur3 Nov 22 '18 at 21:29
• Hi there @g00dnatur3. I'm British, so I was always taught the order of precedence was BODMAS. The "D" being division and "M" being multiplication. These are equal precedence. In cases of equal precedence, you just operate from left to right. So for this calculation, in absence of brackets grouping the `personalrate` and `blocktime` together, I would perform the division first (`network hashrate / personalrate`), then multiply the result by `blocktime`. (Also, I've used the same layout of the calculation from the link in the question.) – Richard Horrocks Nov 22 '18 at 21:40
• Admittedly this would be clearer with a set of brackets around the two hash rates being divided, but again, I was following the format outlined in the link in the original question. – Richard Horrocks Nov 22 '18 at 21:43
• (Okay, looking at the question in the OP link, there are brackets, but looking at the accepted answer, there aren't. I think Afri is from Germany, so likely has a similar European way of doing things.) – Richard Horrocks Nov 22 '18 at 21:51

## Not an answer, just advice...

It doesn't really matter if you find a block or not, because in the process of doing so the graphics card of the laptop will eventually die. Laptops are not meant to be used that way.

• The trick is to mine enough value from the network to cover the costs of replacing the hardware... :) – Richard Horrocks Apr 24 '17 at 14:02
• No, the trick is to replace hardware -and- make a profit.. ;-) – bshea Dec 30 '17 at 14:54