<p>Well doesn't that figure, the moment I ask the question my google-fu kicks in.</p>

<p><a href="https://en.bitcoin.it/wiki/Target">This wiki article</a> states:</p>

<blockquote>
  <p>A single retarget never changes the target by more than a factor of 4
  either way to prevent large changes in difficulty.</p>
</blockquote>

CC BY-SA 3.0
2012-06-23T00:08:08.857Z
Ah, gotta love moments like this! ;)
ThePiachu
CC BY-SA 3.0
2012-06-23T00:13:12.873Z
Yeah, I seriously think there's something about the act of phrasing a question for SE that activates some hidden bit of gray matter and creates superior search terms. It's not so annoying when it's an hour later, this one was mere seconds :P
David Perry
CC BY-SA 3.0
2012-06-23T00:27:12.093Z
Well, it's still a good question and a good answer.
ThePiachu
CC BY-SA 3.0
2012-06-23T01:03:21.177Z
Interesting that the article would consider a change from the currently difficult of 1,726,567 to either 5,000,000 or 500,000 as not being a large change... I guess it's considering it from a logarithmic perspective?
Highly Irregular
CC BY-SA 3.0
2012-06-22T23:51:53.167Z
2012-06-22T23:51:53.167Z
David Perry
<p>The difficulty never changes by more than a factor of 4 (except for in a special case that only applies on testnet).</p>

<p>The code that enforces this is <a href="https://github.com/bitcoin/bitcoin/blob/d62a1947be5350ed60066ccacc7aba43bbdf48fb/src/main.cpp#L875">here</a>.</p>

CC BY-SA 3.0
2012-06-23T01:25:31.647Z
2012-06-23T01:25:31.647Z
Chris Moore
<p>I seem to recall, long ago, being told that difficulty couldn't change more than a certain amount at each retarget, but I can't seem to find what that factor is (or even confirmation that such a factor exists) no matter how hard I google. Does such a factor exist and if so what is its value?</p>

<protocol><difficulty>
Is there a maximum factor by which difficulty can change?
David Perry
# Is there a maximum factor by which difficulty can change?

(Asked by: username_0 on 2012-06-22)

I seem to recall, long ago, being told that difficulty couldn't change more than a certain amount at each retarget, but I can't seem to find what that factor is (or even confirmation that such a factor exists) no matter how hard I google. Does such a factor exist and if so what is its value?

**Tags:** protocol, difficulty


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## 2 answers

### Answer by username_3 on 2012-06-23. Score: 11 | Accepted answer

The difficulty never changes by more than a factor of 4 (except for in a special case that only applies on testnet).

The code that enforces this is [here](https://github.com/bitcoin/bitcoin/blob/d62a1947be5350ed60066ccacc7aba43bbdf48fb/src/main.cpp#L875).


---

### Answer by username_0 on 2012-06-22. Score: 8

Well doesn't that figure, the moment I ask the question my google-fu kicks in.

[This wiki article](https://en.bitcoin.it/wiki/Target) states:

> A single retarget never changes the target by more than a factor of 4
> either way to prevent large changes in difficulty.

> **Comments:**
> **username_1**: Ah, gotta love moments like this! ;)  
> **username_0**: Yeah, I seriously think there's something about the act of phrasing a question for SE that activates some hidden bit of gray matter and creates superior search terms. It's not so annoying when it's an hour later, this one was mere seconds :P  
> **username_1**: Well, it's still a good question and a good answer.  
> **username_2**: Interesting that the article would consider a change from the currently difficult of 1,726,567 to either 5,000,000 or 500,000 as not being a large change... I guess it's considering it from a logarithmic perspective?  

---

