<p>A standard laptop CPU provides around <a href="https://bitcointalk.org/index.php?topic=1628.0" rel="nofollow">2-8 Mhash/sec</a>. An ATI 5870 video card, which has one the best efficiency/cost ratios, mines at about <a href="https://en.bitcoin.it/wiki/Mining_hardware_comparison" rel="nofollow">400 Mhash/sec</a>, and at the moment, the Bitcoin network has a total hashing power of about 12,460,000 Mhash/sec, which equals 31,150 5870 video cards.</p>

<p>So someone would need to invest about 10 million USD just to buy video cards, without including the cost of assembly and other hardware like mother boards, power supplies etc. It is possible to design custom hardware to do Bitcoin mining using an <a href="http://www.techthefuture.com/technology/the-future-hardware-of-bitcoin-mining/" rel="nofollow">ASIC</a>, which might have ten times better efficiency/cost ratio.</p>

<p>But it will be always too expensive to execute a 51% attack to justify just by the profit from the security breach because the Bitcoin network hash rate gets adjusted to the value of a Bitcoin -- in another words, people buy more mining hardware when the price of a Bitcoin goes up.</p>

CC BY-SA 3.0
2011-09-14T19:11:55.537Z
2011-09-14T20:45:52.147Z
2011-09-14T20:45:52.147Z
Serith
<p>A i3 laptop will get around 2Mhash.</p>

<p>The entire network stands at around 12Thash.</p>

<p>So around 3 million laptops to get 50%.</p>

<p>There are better ways to mine though.</p>

CC BY-SA 3.0
2011-09-14T19:01:10.607Z
2011-09-14T19:01:10.607Z
MaxSan
<p>What is the hash rate of a standard laptop using the default client and what is it for the whole of Bitcoin? I am interested in this, because I want to understand what it would take to get to 51% of hashing power (is this what it is called?) </p>

CC BY-SA 3.0
2015-06-09T22:56:15.393Z
I'm voting to close this question as off-topic because it's too localized in time.
Murch
CC BY-SA 3.0
2011-09-14T19:00:44.930Z
possible duplicate of [How much Bitcoin will I mine right now with hardware X?](http://bitcoin.stackexchange.com/questions/118/how-much-bitcoin-will-i-mine-right-now-with-hardware-x)
ripper234
CC BY-SA 3.0
2011-09-14T19:00:52.747Z
See also http://bitcoin.stackexchange.com/questions/485/how-can-i-compute-mining-profitability
ripper234
CC BY-SA 3.0
2011-09-14T19:20:07.303Z
@ripper This is not an **exact** duplicate of the other question.  This question specifically asks about the hashing power of the entire network, and that question does not mention that.
Michael McGowan
CC BY-SA 3.0
2011-09-14T19:20:21.780Z
@PersonVotingToClose Please only vote to close as an **exact** duplicate when the question is actually an **exact** duplicate and not just similar.
Michael McGowan
CC BY-SA 3.0
2011-09-14T19:22:18.563Z
@Michael - I would like for the part that asks about a specific machine's performance to be removed from this question. If it asked only about the total hash power, it wouldn't be a dup. The answers that this question are generating are answers to the questions I linked to.
ripper234
CC BY-SA 3.0
2011-09-14T19:25:26.497Z
@ripper So perhaps some edits are in order or something.  If Question 1 has parts A and B and Question 2 just has part A, Question 1 cannot be an **exact** duplicate of Question 2.
Michael McGowan
CC BY-SA 3.0
2011-09-14T19:35:36.340Z
let us [continue this discussion in chat](http://chat.stackexchange.com/rooms/1348/discussion-between-ripper234-and-michael-mcgowan)
ripper234
CC BY-SA 3.0
2011-09-14T20:48:39.073Z
I got such a great answer, so I believe it is too late to edit the question. Having the two parts of the question as separate questions would really reduce the value of this question, so I believe it is good as it is.
David
CC BY-SA 3.0
2011-09-14T21:26:20.123Z
@David If what you want to find out is the ratio of your hash rate to the total hash rate then the title of the question should be changed. This question could also be closed as "too localized in time".
D.H.
CC BY-SA 3.0
2011-09-14T22:05:23.410Z
@D.H. I have edited the question, to make it less localized in time.
David
<security><majority-attack>
How many consumer computers would it take to launch a 51% attack
David
# How many consumer computers would it take to launch a 51% attack

(Asked by: username_0 on 2011-09-14)

What is the hash rate of a standard laptop using the default client and what is it for the whole of Bitcoin? I am interested in this, because I want to understand what it would take to get to 51% of hashing power (is this what it is called?)

**Tags:** security, majority-attack

> **Comments:**
> **username_2**: possible duplicate of [How much Bitcoin will I mine right now with hardware X?](http://bitcoin.stackexchange.com/questions/118/how-much-bitcoin-will-i-mine-right-now-with-hardware-x)  
> **username_2**: See also http://bitcoin.stackexchange.com/questions/485/how-can-i-compute-mining-profitability  
> **username_3**: @ripper This is not an **exact** duplicate of the other question.  This question specifically asks about the hashing power of the entire network, and that question does not mention that.  
> **username_3**: @PersonVotingToClose Please only vote to close as an **exact** duplicate when the question is actually an **exact** duplicate and not just similar.  
> **username_2**: @username_3 - I would like for the part that asks about a specific machine's performance to be removed from this question. If it asked only about the total hash power, it wouldn't be a dup. The answers that this question are generating are answers to the questions I linked to.  
> **username_3**: @ripper So perhaps some edits are in order or something.  If Question 1 has parts A and B and Question 2 just has part A, Question 1 cannot be an **exact** duplicate of Question 2.  
> **username_2**: let us [continue this discussion in chat](http://chat.stackexchange.com/rooms/1348/discussion-between-username_2-and-username_3)  
> **username_0**: I got such a great answer, so I believe it is too late to edit the question. Having the two parts of the question as separate questions would really reduce the value of this question, so I believe it is good as it is.  
> **username_4**: @username_0 If what you want to find out is the ratio of your hash rate to the total hash rate then the title of the question should be changed. This question could also be closed as "too localized in time".  
> **username_0**: @D.H. I have edited the question, to make it less localized in time.  
> **username_1**: I'm voting to close this question as off-topic because it's too localized in time.  

---

## 2 answers

### Answer by username_5 on 2011-09-14. Score: 3 | Accepted answer

A standard laptop CPU provides around [2-8 Mhash/sec](https://bitcointalk.org/index.php?topic=1628.0). An ATI 5870 video card, which has one the best efficiency/cost ratios, mines at about [400 Mhash/sec](https://en.bitcoin.it/wiki/Mining_hardware_comparison), and at the moment, the Bitcoin network has a total hashing power of about 12,460,000 Mhash/sec, which equals 31,150 5870 video cards.

So someone would need to invest about 10 million USD just to buy video cards, without including the cost of assembly and other hardware like mother boards, power supplies etc. It is possible to design custom hardware to do Bitcoin mining using an [ASIC](http://www.techthefuture.com/technology/the-future-hardware-of-bitcoin-mining/), which might have ten times better efficiency/cost ratio.

But it will be always too expensive to execute a 51% attack to justify just by the profit from the security breach because the Bitcoin network hash rate gets adjusted to the value of a Bitcoin -- in another words, people buy more mining hardware when the price of a Bitcoin goes up.


---

### Answer by username_6 on 2011-09-14. Score: 2

A i3 laptop will get around 2Mhash.

The entire network stands at around 12Thash.

So around 3 million laptops to get 50%.

There are better ways to mine though.


---

