How Long Should a Research Paper Be? Data from 61,519 Examples

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I analyzed a random sample of 61,519 full-text research papers, uploaded to PubMed Central between the years 2016 and 2021, in order to answer the questions:

What is the typical overall length of a research paper? and how long should each section be?

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

Here’s a summary of the key findings

1- The median length of a research paper is 4,133 words (equivalent to 166 sentences or 34 paragraphs), excluding the abstract and references, with 90% of papers being between 2,023 and 8,284 words.

2- A typical article is divided in the following way:

  • Introduction section: 14.6% of the total word count.
  • Methods section: 29.7% of the total word count.
  • Results section: 26.2% of the total word count.
  • Discussion section: 29.4% of the total word count.

Notice that the Materials and methods is the longest section of a professionally written article. So always write this section in enough depth to provide the readers with the necessary details that allow them to replicate your study if they wanted to without requiring further information.

Overall length of a research paper

Let’s start by looking at the maximum word count allowed in some of the well-known journals. Note that the numbers reported in this table include the Abstract, Figure legends and References unless otherwise specified:

JournalMaximum Length Allowed
for Original Research Papers		Maximum Length Allowed
for Review Papers
Nature9,000 words [2]9,000 words [2]
Elsevier Journals8,000 words8,000 words
Cancer5,000 words6,000 words
Neurology4,850 words [1,2]5,350 words [1,2]
Science4,500 words6,000 words
Blood4,000 words [1,2]4,000 words [1,2]
Annals of Internal Medicine3,775 words [2]4,275 words [2]
Journal of Clinical Psychiatry3,250 words [1,2]5,250 words [1,2]
Pediatrics3,000 words4,000 words

[1] excluding figure legends
[2] excluding references

⚠ Note
A review paper is either a systematic review or a meta-analysis, and an original research paper refers to either an observational or an experimental study conducted by the authors themselves.

Notice the large variability between these journals: The maximum number of words allowed ranges between 3,000 and 9,000 words.

Next, let’s look at our data.

Here’s a table that describes the length of a research paper in our sample:

Article Length
(Word Count)		Article Length
(Sentence Count)		Article Length
(Paragraph Count)
Minimum271 words12 sentences4 paragraphs
25th Percentile3,118 words125 sentences26 paragraphs
50th Percentile (Median)4,113 words166 sentences34 paragraphs
Mean4,539 words184 sentences40 paragraphs
75th Percentile5,494 words220 sentences46 paragraphs
Maximum48,163 words3,438 sentences1,736 paragraphs

90% of research papers have a word count between 2,023 and 8,284. So it will be a little weird to see a word count outside of this range.

Our data also agree that a typical review paper is a little bit longer than a typical original research paper but not by much (3,858 vs 3,708 words).

Length of each section in a research article

The median article with an IMRaD structure (i.e. contains the following sections: Introduction, Methods, Results and Discussion) is in general characterized by a short 553 words introduction. And the methods, results and discussion sections are about twice the size of the introduction:

Median Word CountLength in Percent
of the Total Word Count
Introduction Section553 words14.6%
Methods Section1,126 words29.7%
Results Section991 words26.2%
Discussion Section1,115 words29.5%

For more information, see:

References

  • 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.