Paragraph Length: Data from 9,830 Research Papers

I analyzed a random sample of 9,830 full-text research papers, uploaded to PubMed Central between the years 2016 and 2021, to answer the question:

How long should a paragraph be in a research paper?

I used the BioC API to download the data (see the References section below).

Paragraph length

Our sample of 9,830 research articles had 325,500 paragraphs. The following table summarizes the length of these paragraphs::

Number of Sentences in a ParagraphNumber of Words in a Paragraph
Minimum1 sentence1 word
5th Percentile1 sentence19 words
25th Percentile2 sentences65 words
50th Percentile (Median)4 sentences109 words
Mean4.8 sentences125.2 words
75th Percentile6 sentences167 words
95th Percentile11 sentences286 words
Maximum61 sentences1,847 words

From these data we can conclude that:

  • The median paragraph length is 4 sentences (or 109 words), and most paragraphs are between 2 and 6 sentences (or 65 and 167 words).
  • A paragraph can be just one sentence long. In fact, 13% (n=42,349) of all paragraphs in our sample were 1 sentence long.
  • 90% of paragraphs were between 19 and 286 words (1 and 11 sentences). So, a paragraph shorter than 19 words can be considered too short; and a paragraph longer than 286 words (or 11 sentences) can be considered too long.

Paragraph length in each section of the research paper

A research paper is usually divided into 4 sections: Introduction, Methods, Results, and Discussion. The following table shows the median paragraph length for each of these sections:

Median Paragraph Length
Research Paper SectionSentence CountWord Count
Introduction4 sentences113 words
Methods4 sentences92 words
Results4 sentences105 words
Discussion5 sentences131 words

The Discussion section has slightly longer paragraphs than other sections with a median of 5 sentences and 131 words.

Paragraph length in different types of studies

The data suggests that paragraph length did not differ for different study designs. Review papers (systematic reviews and meta-analyses) had almost the same paragraph length (median=103 words) as original research papers (median=110 words).


  • Comeau DC, Wei CH, Islamaj Doğan R, and Lu Z. PMC text mining subset in BioC: about 3 million full text articles and growing, Bioinformatics, btz070, 2019.

Further reading