Are there general guidelines regarding the length of sentences in Japanese written text for the sake of readability?


Inspired by [this
question](https://writing.stackexchange.com/questions/43752/what-should-be-
the-ideal-length-of-sentences-in-a-blog-post-for-ease-of-reading), I'm curious
as to whether there are similar guidelines for the length of Japanese
sentences (Maybe in Japanese clauses are more relevant?) to maximize
readability, whether that length is measured by # of kana or # of kanji or
some other measure. Sources regarding online writing in blogs and published
non-fiction/fiction are particularly interesting.




This
[site](http://www.kariness.com/entry/2018/02/04/%E8%AA%AD%E3%81%BF%E3%82%84%E3%81%99%E3%81%84%E6%96%87%E7%AB%A0%E3%81%AE%E9%95%B7%E3%81%95%E3%81%A8%E3%81%AF%EF%BC%9F_%E4%B8%80%E6%96%87%E3%81%AE%E9%95%B7%E3%81%95%E3%82%92%E8%AA%BF%E3%81%B9%E3%81%A6%E3%81%BF)
talks about the sentence length using NHK,朝日新聞,日経 as a guideline. The author
picked up 5 free article from each company. The methodology is splitting the
text by the period symbol and then counting the letters in the sentences.

[![enter image description
here](https://i.stack.imgur.com/VTlGL.png)](https://i.stack.imgur.com/VTlGL.png)

The sentences from NHK are longer than the sentences from other newspaper
companies. NHK could be using different guidelines. Then the author speculates
about the case of text by famous novelists.

[![enter image description
here](https://i.stack.imgur.com/Ncd1I.png)](https://i.stack.imgur.com/Ncd1I.png)

So, around 20 to 22 words in the sentence is common in those famous novels.
Then the author concludes,

> **結論！ 20文字前半がオススメ！**
> これまでの内容をまとめると、「読みやすい文章、気に入られる文章は20文字前半を1文として構成されている」ということみたいです。

All in all, sentences that are easy to read and well liked are made up of
around 20 words.

Thanks for mentioning by Chocolate, I mixed up the concept of "line length",
"bunsetsu-based line breaking", and " **the sentence length** " which you are
looking for. The following explanation is about line-length and bunsetsu-based
layout. It might be redundant but could be of help for you. I will leave it
here.

* * *

This must be called 「行{ぎょう}長{ちょう}」: "line length". This
[blog](https://terkel.jp/archives/2015/08/line-length/) says,

**

        日本語で書かれたデザインの本でも和文横組みのガイドラインを探してみま

** **

したが、あまり見つけられていません。[『デザインの教室
手を動かして学ぶデザ](https://www.amazon.co.jp/gp/product/4844359797/ref=as_li_ss_tl?ie=UTF8&linkCode=sl1&tag=terkel-22&linkId=8fd8602d653779ef3687eb9d3c472902)

** **

[イントレーニング』](https://www.amazon.co.jp/gp/product/4844359797/ref=as_li_ss_tl?ie=UTF8&linkCode=sl1&tag=terkel-22&linkId=8fd8602d653779ef3687eb9d3c472902)では20字から30字程度が読みやすいとし、15字は「少し短

** **

い」、40字は「あまり推奨できない」、50字は「限界を超えている」とのことで

** **

す。[『タイポグラフィの基本ルール』](https://www.amazon.co.jp/gp/product/4797359226/ref=as_li_ss_tl?ie=UTF8&linkCode=sl1&tag=terkel-22&linkId=e6daac99c04ca70550de79c6ae463ef2)では、30字から40字程度が最長、13字から

15字程度を最短としています。

**

> _I was searching a guideline about horizontal writing of Japanese text among
> books of a design written in Japanese, but I could find little._ 『デザインの教室
> 手を動かして学ぶデザイントレーニング』 _says "approximately from 20 letters to 30 letters" are
> easy to read, 15 letters are "a little bit short", 40 letters are "can not
> recommend a lot", 50 letters are "beyond the limit"._ 『タイポグラフィの基本ルール』 _says
> "approximately from 30 letters to 40 letters" are the longest, from 13
> letters to 15 letters are the shortest._

* * *

According to [文節単位を考慮した文字配置の工夫がもたらす日本語電子リーダーの可読性向上 : Readability of Japanese
Electronic Text with Bunsetsu-based
Layouts](https://www.jstage.jst.go.jp/article/tjsai/32/2/32_A-AI30/_pdf) by
"大日本印刷株式会社 : _Dai Nippon Printing Co., Ltd._ / 公立はこだて未来大学 : _Future University
Hakodate_ ", splitting sentence by bunsetsu-segments makes easier to read. The
following is the excerpt from the abstract of the authors.

> **_In Experiment I, we investigate the effectiveness of the layout with
> bunsetsu-based line breaking. A bunsetsu-based linefeed layout breaks a line
> between bunsetsu segments, i.e., splitting a bunsetsu segment is prohibited.
> The reading speed for the bunsetsu-based linefeed layout was faster compared
> to the conventional text layout with line lengths of 5–40 characters per
> line._**

[![enter image description
here](https://i.stack.imgur.com/UfoNL.jpg)](https://i.stack.imgur.com/UfoNL.jpg)




This
[site](http://www.kariness.com/entry/2018/02/04/%E8%AA%AD%E3%81%BF%E3%82%84%E3%81%99%E3%81%84%E6%96%87%E7%AB%A0%E3%81%AE%E9%95%B7%E3%81%95%E3%81%A8%E3%81%AF%EF%BC%9F_%E4%B8%80%E6%96%87%E3%81%AE%E9%95%B7%E3%81%95%E3%82%92%E8%AA%BF%E3%81%B9%E3%81%A6%E3%81%BF)
talks about the sentence length using NHK,朝日新聞,日経 as a guideline. The author
picked up 5 free article from each company. The methodology is splitting the
text by the period symbol and then counting the letters in the sentences.

[![enter image description
here](https://i.stack.imgur.com/VTlGL.png)](https://i.stack.imgur.com/VTlGL.png)

The sentences from NHK are longer than the sentences from other newspaper
companies. NHK could be using different guidelines. Then the author speculates
about the case of text by famous novelists.

[![enter image description
here](https://i.stack.imgur.com/Ncd1I.png)](https://i.stack.imgur.com/Ncd1I.png)

So, around 20 to 22 words in the sentence is common in those famous novels.
Then the author concludes,

> **結論！ 20文字前半がオススメ！**
> これまでの内容をまとめると、「読みやすい文章、気に入られる文章は20文字前半を1文として構成されている」ということみたいです。

All in all, sentences that are easy to read and well liked are made up of
around 20 words.

Thanks for mentioning by Chocolate, I mixed up the concept of "line length",
"bunsetsu-based line breaking", and " **the sentence length** " which you are
looking for. The following explanation is about line-length and bunsetsu-based
layout. It might be redundant but could be of help for you. I will leave it
here.

* * *

This must be called 「行{ぎょう}長{ちょう}」: "line length". This
[blog](https://terkel.jp/archives/2015/08/line-length/) says,

**

        日本語で書かれたデザインの本でも和文横組みのガイドラインを探してみま

** **

したが、あまり見つけられていません。[『デザインの教室
手を動かして学ぶデザ](https://www.amazon.co.jp/gp/product/4844359797/ref=as_li_ss_tl?ie=UTF8&linkCode=sl1&tag=terkel-22&linkId=8fd8602d653779ef3687eb9d3c472902)

** **

[イントレーニング』](https://www.amazon.co.jp/gp/product/4844359797/ref=as_li_ss_tl?ie=UTF8&linkCode=sl1&tag=terkel-22&linkId=8fd8602d653779ef3687eb9d3c472902)では20字から30字程度が読みやすいとし、15字は「少し短

** **

い」、40字は「あまり推奨できない」、50字は「限界を超えている」とのことで

** **

す。[『タイポグラフィの基本ルール』](https://www.amazon.co.jp/gp/product/4797359226/ref=as_li_ss_tl?ie=UTF8&linkCode=sl1&tag=terkel-22&linkId=e6daac99c04ca70550de79c6ae463ef2)では、30字から40字程度が最長、13字から

15字程度を最短としています。

**

> _I was searching a guideline about horizontal writing of Japanese text among
> books of a design written in Japanese, but I could find little._ 『デザインの教室
> 手を動かして学ぶデザイントレーニング』 _says "approximately from 20 letters to 30 letters" are
> easy to read, 15 letters are "a little bit short", 40 letters are "can not
> recommend a lot", 50 letters are "beyond the limit"._ 『タイポグラフィの基本ルール』 _says
> "approximately from 30 letters to 40 letters" are the longest, from 13
> letters to 15 letters are the shortest._

* * *

According to [文節単位を考慮した文字配置の工夫がもたらす日本語電子リーダーの可読性向上 : Readability of Japanese
Electronic Text with Bunsetsu-based
Layouts](https://www.jstage.jst.go.jp/article/tjsai/32/2/32_A-AI30/_pdf) by
"大日本印刷株式会社 : _Dai Nippon Printing Co., Ltd._ / 公立はこだて未来大学 : _Future University
Hakodate_ ", splitting sentence by bunsetsu-segments makes easier to read. The
following is the excerpt from the abstract of the authors.

> **_In Experiment I, we investigate the effectiveness of the layout with
> bunsetsu-based line breaking. A bunsetsu-based linefeed layout breaks a line
> between bunsetsu segments, i.e., splitting a bunsetsu segment is prohibited.
> The reading speed for the bunsetsu-based linefeed layout was faster compared
> to the conventional text layout with line lengths of 5–40 characters per
> line._**

[![enter image description
here](https://i.stack.imgur.com/UfoNL.jpg)](https://i.stack.imgur.com/UfoNL.jpg)

