<p>If you really wanted to know you could use models of reading behaviour - e.g. EZ-Reader or Swift. The Rayner reviews are the classic go-to to outlne this kind of thing:</p>

<p><a href="https://netfiles.uiuc.edu/kiel/www/590CT/Articles--Eye%20Movements/Rayner_2009_QJEP.pdf">Rayner, K. (2009). Eye movements and attention in reading, scene perception, and visual search. The Quarterly Journal of Experimental Psychology (2006) (Vol. 62, pp. 1457-506).</a></p>

<p>It will depend on:
- Size of text
- Language
- Word frequency
- Word length
- Predictability
- and a whole host of other factors.</p>

<p>Of all the words put together, plus any occasions where regressions to previous words are made because the observer has failed to understand the text.</p>

<p>In practice, it's probably not worth worrying about to this level of complexity so just beta test it with some people and make sure they don't complain that they don't get enough time to read the messages.</p>

CC BY-SA 3.0
2012-06-16T18:00:08.740Z
2012-06-16T18:00:08.740Z
vizzero
<p>I just had a project where I had to figure this out. I found that a good rule of thumb was the following:</p>

<p>$$timeToRead = 1300 + (chars * 65);$$</p>

<p>So that's an initial time of 1300ms to adjust to what you need to be reading and about 65ms per character including spaces.</p>

CC BY-SA 3.0
2012-12-08T20:56:59.127Z
thanks for your answer travis. did you test other models as well, or did you assume a linear relationship? also, do you know the $r^2$ from your dataset?
Jeff
CC BY-SA 3.0
2012-12-09T00:25:37.810Z
This is based purely on a completely unscientific approach of tweaking the numbers and having a script rotate through several different paragraphs of differing lengths.  I read each one slowly enough to completely comprehend what i was reading and if it rotated through too fast, then i increased the timing, too slow, i decreased it until i found the sweet spot. But it would seem that the reading speed for me, at least, is not entirely linear as some paragraphs seemed far faster to read than others of similar lengths.
Travis Beck
CC BY-SA 3.0
2012-12-07T07:18:14.070Z
2012-12-07T22:45:37.523Z
2012-12-07T22:45:37.523Z
Travis Beck
<p>I've studied this a little bit within the context of timing responses to personality test items. General models of reading speed look at both the time to read the words as well as to comprehend. From memory, eye tracking studies have shown how the eyes will often back track to confusing parts of a sentence (apologies for lack of reference).</p>

<p>Some general findings that I've found in my own data on time to answer personality test items of different lengths:</p>

<ul>
<li>Expect an initiation period. I.e., the time between displaying a message and the commencement of reading. In mathematical terms, this will translate to a non-zero constant in your model of reading time as a function of properties of the text.</li>
<li>The more familiar the content and the words are to the reader, the quicker they will be. This translates both in absolute terms that simple words are quicker to read, and also to interactions between individuals and the content.</li>
<li>In general, character count, word count, and syllable count tend to be highly correlated in normal prose. From my own data, these indices tend to have a relatively <strong>linear effect on reading speed</strong>.</li>
<li>More complex sentences (e.g., ones with negation, multiple clauses, etc.) take longer to read. For example, I found that sentences with "not" took systematically longer to process.</li>
<li>Individuals differ substantially in reading speed. Expect to see a distribution of individual differences that is a little bit positive skewed from normal. Thus, if you are designing a system where you determine the length of time text is displayed, you may need to pitch the speed of your system to capture a certain percentage of that distribution (e.g., 95, 99% etc.). Various factors explain variation in reading speed including whether English is a second language and education.</li>
<li>There are also outliers. People get distracted. Thus, there is reading time when people are focussed and there is reading times that incorporate distraction and other processes.</li>
</ul>

<p>More generally, if you have the resources, you can do some pilot testing on a sample of individuals where you time how long people take to read the text, ideally within the context of the application. This could allow you to develop a domain specific model of reading speed.</p>

<p>Although a little tangential, some articles that discuss speed of item responding in a personality testing context include Casey and Tyron (2001) and Wagner-Menghim (2002).</p>

<h3>References</h3>

<ul>
<li>Casey, M.M. &amp; Tryon, W.W. (2001). Validating a double-press method for computer administration of personality inventory items.. Psychological assessment, 13, 521.</li>
<li>Wagner-Menghin, M. (2002). Towards the identification of non-scalable personality
questionnaire respondents: Taking response time into account.
Psychologische Beiträge, 44(1), 62-77.</li>
</ul>

CC BY-SA 3.0
2012-06-16T04:46:00.207Z
2012-12-08T00:46:10.433Z
2012-12-08T00:46:10.433Z
Jeromy Anglim
<p>How does the time needed to read a sentence scale with the number of characters? Or does this time scaling depend on something more than just character count?</p>

<p>For example, let $X$ be the number of characters and $F(X)$ the seconds to read an entire sentence of $X$ characters long. There are 3 options:</p>

<ol>
<li><p><strong>Linear</strong> $F(X) \in \Theta(X)$:  Is the relationship linear? That is, if it takes 0.5 seconds to read "<em>hello</em>", it would take 1.0 second to read "<em>hello world</em>": $F(X) = 0.1 X$</p></li>
<li><p><strong>Sublinear</strong> $F(X) \in o(X)$: Or does it decay? That is, as people read a long sentence, their reading speed increases (crazy example $F(X) = 1 / X$)</p></li>
<li><p><strong>Super-linear</strong> $F(X) \in \omega(X)$: Or is it like quadratic? That is, each additional character ads more time than the previous word? (example: $F(X) = X ^ 2$)</p></li>
</ol>

<p><strong>Which of the above 3 options best describes reading speed based on length of text? Is the specific functional form of this relationship known?</strong></p>

<hr>

<h3>Motivation</h3>

<p>I am creating an iPhone app where I need to show transient confirmation messages. For example, when a user submits a comment, I pop up a message saying "<em>thanks for submitting your comment</em>". Shortly after, the message will fade away. There exist many such transient messages all over my iPhone app. </p>

<p>What I would like to do is to calculate the optimal time to show each message based off of the number of characters in that message. I want users to have enough time to comfortably read the message, but not so long that the message annoys them. The purely UX version of this question is here:</p>

<p><a href="https://ux.stackexchange.com/questions/22520/how-long-does-it-take-to-read-x-number-of-characters">How long does it take to read X number of characters?</a></p>

CC BY-SA 3.0
2012-06-16T00:35:26.213Z
I reposted my comment on ux.stackexchange.com before some mod migrated my question to cogsci.
JoJo
CC BY-SA 3.0
2012-06-16T00:42:31.290Z
Honestly this is fine on either site, and will probably get different answers on both; more focused on academic research here, with probably a more practical and simple (possibly less precise but more actionable) on UX. I'm fine with it being on both if Cog Sci welcomes it
Zelda
CC BY-SA 3.0
2012-06-16T01:05:06.613Z
I made a significant edit to the question to make it focus on the scientific aspect of the question. Please edit the [UX version](http://ux.stackexchange.com/questions/22520/how-long-does-it-take-to-read-x-number-of-characters) to focus on the UX-part and not be a copy-and-paste of the original Q. If you think I changed the spirit too much, feel free to roll-back my edits, but keep in mind we are not UX and prefer scientific questions.
Artem Kaznatcheev
CC BY-SA 3.0
2012-06-16T01:22:13.033Z
@J.R. I think your answer is fine, you state the important features (that words matter more than characters) and that is is weird to expect sub-linear. However, if you feel inclined to expand your answer with more background on the psychology of reading, then that would be super!
Artem Kaznatcheev
CC BY-SA 3.0
2012-06-16T01:32:52.050Z
I agree with @ArtemKaznatcheev. This question is very interesting. People do not read text in a linear fashion. Instead our eyes jump around, just like when we process a visual scene. However, I'm not aware of the effects of text length on reading speed. If I find something I will make an answer.
Vielle
<experimental-psychology><reading><linguistics><human-factors>
How long does it take to read a sentence with X number of characters?
JoJo
# How long does it take to read a sentence with X number of characters?

(Asked by: username_0 on 2012-06-15)

How does the time needed to read a sentence scale with the number of characters? Or does this time scaling depend on something more than just character count?

For example, let $X$ be the number of characters and $F(X)$ the seconds to read an entire sentence of $X$ characters long. There are 3 options:

1. **Linear** $F(X) \in \Theta(X)$: Is the relationship linear? That is, if it takes 0.5 seconds to read "*hello*", it would take 1.0 second to read "*hello world*": $F(X) = 0.1 X$
2. **Sublinear** $F(X) \in o(X)$: Or does it decay? That is, as people read a long sentence, their reading speed increases (crazy example $F(X) = 1 / X$)
3. **Super-linear** $F(X) \in \omega(X)$: Or is it like quadratic? That is, each additional character ads more time than the previous word? (example: $F(X) = X ^ 2$)

**Which of the above 3 options best describes reading speed based on length of text? Is the specific functional form of this relationship known?**

---

### Motivation

I am creating an iPhone app where I need to show transient confirmation messages. For example, when a user submits a comment, I pop up a message saying "*thanks for submitting your comment*". Shortly after, the message will fade away. There exist many such transient messages all over my iPhone app.

What I would like to do is to calculate the optimal time to show each message based off of the number of characters in that message. I want users to have enough time to comfortably read the message, but not so long that the message annoys them. The purely UX version of this question is here:

[How long does it take to read X number of characters?](https://ux.stackexchange.com/questions/22520/how-long-does-it-take-to-read-x-number-of-characters)

**Tags:** experimental-psychology, reading, linguistics, human-factors

> **Comments:**
> **username_0**: I reposted my comment on ux.stackexchange.com before some mod migrated my question to cogsci.  
> **username_1**: Honestly this is fine on either site, and will probably get different answers on both; more focused on academic research here, with probably a more practical and simple (possibly less precise but more actionable) on UX. I'm fine with it being on both if Cog Sci welcomes it  
> **username_2**: I made a significant edit to the question to make it focus on the scientific aspect of the question. Please edit the [UX version](http://ux.stackexchange.com/questions/22520/how-long-does-it-take-to-read-x-number-of-characters) to focus on the UX-part and not be a copy-and-paste of the original Q. If you think I changed the spirit too much, feel free to roll-back my edits, but keep in mind we are not UX and prefer scientific questions.  
> **username_2**: @J.R. I think your answer is fine, you state the important features (that words matter more than characters) and that is is weird to expect sub-linear. However, if you feel inclined to expand your answer with more background on the psychology of reading, then that would be super!  
> **username_3**: I agree with @ArtemKaznatcheev. This question is very interesting. People do not read text in a linear fashion. Instead our eyes jump around, just like when we process a visual scene. However, I'm not aware of the effects of text length on reading speed. If I find something I will make an answer.  

---

## 3 answers

### Answer by username_7 on 2012-06-16. Score: 11 | Accepted answer

I've studied this a little bit within the context of timing responses to personality test items. General models of reading speed look at both the time to read the words as well as to comprehend. From memory, eye tracking studies have shown how the eyes will often back track to confusing parts of a sentence (apologies for lack of reference).

Some general findings that I've found in my own data on time to answer personality test items of different lengths:

* Expect an initiation period. I.e., the time between displaying a message and the commencement of reading. In mathematical terms, this will translate to a non-zero constant in your model of reading time as a function of properties of the text.
* The more familiar the content and the words are to the reader, the quicker they will be. This translates both in absolute terms that simple words are quicker to read, and also to interactions between individuals and the content.
* In general, character count, word count, and syllable count tend to be highly correlated in normal prose. From my own data, these indices tend to have a relatively **linear effect on reading speed**.
* More complex sentences (e.g., ones with negation, multiple clauses, etc.) take longer to read. For example, I found that sentences with "not" took systematically longer to process.
* Individuals differ substantially in reading speed. Expect to see a distribution of individual differences that is a little bit positive skewed from normal. Thus, if you are designing a system where you determine the length of time text is displayed, you may need to pitch the speed of your system to capture a certain percentage of that distribution (e.g., 95, 99% etc.). Various factors explain variation in reading speed including whether English is a second language and education.
* There are also outliers. People get distracted. Thus, there is reading time when people are focussed and there is reading times that incorporate distraction and other processes.

More generally, if you have the resources, you can do some pilot testing on a sample of individuals where you time how long people take to read the text, ideally within the context of the application. This could allow you to develop a domain specific model of reading speed.

Although a little tangential, some articles that discuss speed of item responding in a personality testing context include Casey and Tyron (2001) and Wagner-Menghim (2002).

### References

* Casey, M.M. & Tryon, W.W. (2001). Validating a double-press method for computer administration of personality inventory items.. Psychological assessment, 13, 521.
* Wagner-Menghin, M. (2002). Towards the identification of non-scalable personality
  questionnaire respondents: Taking response time into account.
  Psychologische Beiträge, 44(1), 62-77.


---

### Answer by username_4 on 2012-06-16. Score: 7

If you really wanted to know you could use models of reading behaviour - e.g. EZ-Reader or Swift. The Rayner reviews are the classic go-to to outlne this kind of thing:

[Rayner, K. (2009). Eye movements and attention in reading, scene perception, and visual search. The Quarterly Journal of Experimental Psychology (2006) (Vol. 62, pp. 1457-506).](https://netfiles.uiuc.edu/kiel/www/590CT/Articles--Eye%20Movements/Rayner_2009_QJEP.pdf)

It will depend on:
- Size of text
- Language
- Word frequency
- Word length
- Predictability
- and a whole host of other factors.

Of all the words put together, plus any occasions where regressions to previous words are made because the observer has failed to understand the text.

In practice, it's probably not worth worrying about to this level of complexity so just beta test it with some people and make sure they don't complain that they don't get enough time to read the messages.


---

### Answer by username_5 on 2012-12-07. Score: 3

I just had a project where I had to figure this out. I found that a good rule of thumb was the following:

$$timeToRead = 1300 + (chars \* 65);$$

So that's an initial time of 1300ms to adjust to what you need to be reading and about 65ms per character including spaces.

> **Comments:**
> **username_6**: thanks for your answer travis. did you test other models as well, or did you assume a linear relationship? also, do you know the $r^2$ from your dataset?  
> **username_5**: This is based purely on a completely unscientific approach of tweaking the numbers and having a script rotate through several different paragraphs of differing lengths.  I read each one slowly enough to completely comprehend what i was reading and if it rotated through too fast, then i increased the timing, too slow, i decreased it until i found the sweet spot. But it would seem that the reading speed for me, at least, is not entirely linear as some paragraphs seemed far faster to read than others of similar lengths.  

---

