Sentence Length

There is no hard and fast rule that dictates the maximum word limit that a sentence should follow. While endeavouring to limit your sentence length - as well as breaking up very long sentences into two or more (see exampleLinks to an external site.) - is generally good practice, there are a number of factors to be taken into consideration.

Reader Attention

In academic writing, the average sentence length is typically between 15-20 words. With this in mind, many scholars look to keep their sentences under 25 words in length. This is because there is a notable drop in the reader's ability to retain information in sentences that are longer than 25 words (2Links to an external site.). Though imposing a rigid 25 word limit to your academic sentences may be too prescriptive, a good general approach is to look to wrap up sentences over 20 words at the nearest applicable point.

Varying Sentence Length

Most scholars agree that it is important to vary one's sentence length between longer and shorter sentences. This gives your writing rhythm and, therefore, makes it more engaging for the reader. Long and short sentences have different functions within writing (3Links to an external site.). While short sentences transmit 'cut and dry' information that the writer wants the reader to immediately accept, longer sentences take a more circuitous route, allowing the reader to contemplate a topic from different vantage points. Again, it is perhaps too prescriptive to 'ensure all long sentences are immediately followed by a short sentence'; however, interspersing short sentences throughout one's writing does add to its stylistic dynamism. 

Disciplinary Differences

Typically, we observe more longer sentence construction in the Humanities and Social Sciences than in the Medical Sciences and MPLS. This in primarily because the natural science writing style tends to favour the use of simple sentences, which have only one main clause. In the Humanities and Social Sciences, we tend to see more variety between simple sentences and more complex sentence constructions. Consider the examples below:

Oxford Topic Sentences Examples

Sentence Length & Discipline

Below are examples of the stylistic differences that we see with Oxford disciplinary writing. Please consider the examples and analysis:

Extract A: Humanities

The work of the playwright Joanna Baillie illustrates the continuation of these ideas in the late eighteenth and early nineteenth centuries. In 1798, Baillie set out to compose a series of plays that illustrate ‘all that language of the agitated soul’, an idea strikingly similar to Johnson as she repeats the word ‘agitated’. [20] Her project originates in the belief that ‘any person harbours in his breast, concealed from the world’s eye, some powerful rankling passion of what kind soever it may be’, which echoes Johnson’s principle of universality. [21] This also suggests that the passions that animate men are invisible to the naked eye. Baillie’s plays were part of a scheme to show the effects of a mastering passion on a character, and the ways in which that central passion manifests itself differently in comedy and in tragedy, the ‘concealed passion’ externalised in the process. [22] Passions were thus at the heart of the drama of the period...

Extract B: MPLS

The method employed to slow extract the SFT beam is known as Constant-Optics Slow Extraction (COSE) [43]. In COSE, the machine’s beam rigidity Bρ is slowly varied as a function of time, so that the reference momentum p0 changes accordingly. Since all magnetic fields in the lattice are varied with Bρ, all resonant particles ‘see’ the same optics as the resonant tune is swept. This eliminates the linear and nonlinear chromatic perturbations that are present in a ‘conventional’ quadrupole sweep. Then, a particle’s betatron tune Qx,i evolves as follows: ...

Analysis

From a disciplinary standpoint, both extracts are well written. In the Humanities example, we observe a higher frequency of very long sentences (of 25 words or over). However, some shorter sentences have been included to ensure the writing doesn't sound overly meandering or exploratory. The MPLS example doesn't have any sentences of 25 words or more. The author opts for mainly short simple sentences (with one independent clause) but, again, includes for one complex construction ("Since all magnetic fields...") to ensure the writing doesn't sound overly robotic or monotonous.