The length of your research paper will depend on two factors: (1) the type of paper you intend to write, i.e. research paper, review paper, method paper, technical note, essay, forum piece, commentary, or short communication, and (2) the page or word limit requirements of the journal for that type of paper. These limits can also influence the type of paper you write, especially following a peer review, where the reviewer may suggest shortening the paper to something more manageable or concise. The first step in writing a research paper is determining your audience (see ‘I’ve never submitted to a journal before. Where do I start?’), which will define the type of paper you will write and thus its length. As an author, you can source more specific guidelines for paper length, including page and figure limits, from the journal website under their own ‘Instructions for authors’ sections.
The general rule of thumb is the shorter the better: more concise papers are more interesting, usually less technical, and are easier to digest.
Practical example for Life Sciences
Within the life sciences, typical research papers must not exceed 7,000 words. Sometimes there are also limits on the number of possible figures. Shorter pieces, such as commentary, forum, and technical papers, are usually <3000 words.
Practical example for Social Sciences
The length of the research paper is almost entirely determined by the journal that you aim to submit to. For example, some publications have strict work limits (e.g. <3000 words) and others have a general upper limit that allows for greater freedom e.g. not exceed 30 double-spaced, 12pt pages excluding references. One can opt for a short report or full research article, although short reports are often reserved for research that reports novel techniques or ground-breaking results.