<p>Excluding complications like difficulty changes and temporary blockchain splits, you can model the block generation time as an <a href="http://en.wikipedia.org/wiki/Exponential_distribution" rel="nofollow noreferrer">exponential distribution</a>.</p>

<p>An exponential distribution has a standard deviation equal to the expectancy value. This predicts a 10 minute standard deviation for Bitcoin.</p>

<hr>

<p>Measuring the actual distribution isn't that easy. While each block contains a timestamp, that timestamp isn't very accurate, and sometimes the time difference between blocks is <a href="https://bitcoin.stackexchange.com/questions/3743/how-can-an-earlier-block-have-a-later-timestamp">even negative</a>.<br>
The timestamp doesn't change over the course of a single share, and some miners deliberately use timestamps deviating from the actual time</p>

CC BY-SA 3.0
2012-09-14T08:57:59.533Z
2012-09-14T09:13:02.550Z
2017-04-13T12:47:33.283Z
CodesInChaos
<p>A block is generated every 10 minutes, on average.
What is the standard deviation of this distribution?</p>

<p>It seems to be a measurable property, not a calculable one.</p>

<p>Is there a chart of the standard dev over time somewhere (should be added to blockchain.info)?</p>

CC BY-SA 3.0
2015-05-21T04:34:49.263Z
Why do you ask about s.e. only versus robust statistics like quantiles?
alancalvitti
<blockchain><block-interval>
What is the standard deviation of block generation times?
ripper234
# What is the standard deviation of block generation times?

(Asked by: username_0 on 2012-09-14)

A block is generated every 10 minutes, on average.
What is the standard deviation of this distribution?

It seems to be a measurable property, not a calculable one.

Is there a chart of the standard dev over time somewhere (should be added to blockchain.info)?

**Tags:** blockchain, block-interval

> **Comments:**
> **username_1**: Why do you ask about s.e. only versus robust statistics like quantiles?  

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## 1 answers

### Answer by username_2 on 2012-09-14. Score: 12 | Accepted answer

Excluding complications like difficulty changes and temporary blockchain splits, you can model the block generation time as an [exponential distribution](http://en.wikipedia.org/wiki/Exponential_distribution).

An exponential distribution has a standard deviation equal to the expectancy value. This predicts a 10 minute standard deviation for Bitcoin.

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Measuring the actual distribution isn't that easy. While each block contains a timestamp, that timestamp isn't very accurate, and sometimes the time difference between blocks is [even negative](https://bitcoin.stackexchange.com/questions/3743/how-can-an-earlier-block-have-a-later-timestamp).  
The timestamp doesn't change over the course of a single share, and some miners deliberately use timestamps deviating from the actual time


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