British English vs. American English: Spelling, Punctuation, and Other Differences in Academic Writing

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Key Takeaways

• The most consequential differences between British and American English in academic writing fall into four categories: spelling patterns, punctuation conventions (especially around quotation marks), grammar rules for collective nouns and verb tenses, and vocabulary.
• Journals and universities almost always specify which variety to use; when they do not, consistency throughout the entire document is the non-negotiable minimum requirement.
• Non-native English speakers are especially prone to unintentional mixing, which reviewers and examiners can interpret as carelessness, even when the research itself is strong.
• A single, carefully enforced setting in your word processor (e.g., setting the proofing language to “English (United States)” or “English (United Kingdom)”) prevents most accidental errors before a manual check is needed.

Contents

• Introduction
• Spelling differences in British and American English
• Punctuation
• Grammar and Verb Usage
• Dates, Numbers, and Formatting
• Vocabulary Differences in Academic and Scientific Contexts
• Style Guides and Their Language Conventions
• Why Consistency Matters More Than Which Variety You Choose
• Choosing the Right Variety for Your Context
• Considerations for Non-Native English Speakers
• International Readability and Clarity
• Frequently Asked Questions

Introduction

English is the dominant language of global academic publishing, but it is not a single, uniform code. British English (BrE) and American English (AmE) differ in ways that go well beyond accent, and those differences carry real consequences for researchers, thesis writers, and journal authors. Journals frequently specify which variety to use and may return manuscripts that do not comply. University examiners can flag inconsistent spelling as evidence of insufficient care. Even subtle mismatches, such as a single “colour” in an otherwise AmE manuscript, can distract reviewers and undermine the apparent professionalism of strong research.

This guide addresses every major category of difference: spelling patterns, punctuation conventions, verb tense and grammar, date and number formatting, vocabulary, and the expectations of major style guides. It also provides practical guidance on choosing a variety, maintaining consistency, and avoiding the most common pitfalls. Where relevant, differences are illustrated with examples drawn from academic and scientific contexts.

Spelling differences in British and American English

Spelling is the most visible category of difference between BrE and AmE, and it is the one most frequently targeted in journal author guidelines and thesis examiner feedback. The differences are systematic, following a small set of recognizable patterns. Learning those patterns is more efficient than memorizing individual words.

Major Spelling Patterns

Pattern	British English	American English
-ise / -ize (verbs)	organise, analyse, recognise, hypothesise	organize, analyze, recognize, hypothesize
-yse / -yze (verbs)	analyse, catalyse, hydrolyse, paralyse	analyze, catalyze, hydrolyze, paralyze
-our / -or (nouns)	colour, behaviour, humour, tumour, labour	color, behavior, humor, tumor, labor
-re / -er (nouns)	centre, fibre, litre, metre, theatre, titre	center, fiber, liter, meter, theater, titer
ae / oe → e	haemoglobin, leukaemia, oestrogen, paediatric	hemoglobin, leukemia, estrogen, pediatric
-ence / -ense	defence, offence, licence (noun), pretence	defense, offense, license, pretense
-ogue / -og	analogue, catalogue, dialogue, homologue	analog, catalog, dialog, homolog
Double l (inflected forms)	labelled, modelled, travelled, cancelled	labeled, modeled, traveled, canceled
-l / -ll (base forms)	fulfil, enrol, distil, instalment	fulfill, enroll, distill, installment
Silent -e in derivatives	ageing, likeable, judgement, liveable	aging, likable, judgment, livable
-ward / -wards	towards, forwards, backwards	toward, forward, backward
-ical / -ic (adjectives)	anatomical, morphological, serological	anatomic, morphologic, serologic (also -ical)

The -ise vs. -ize Question

This is the single most debated spelling distinction in academic writing. AmE uses -ize exclusively. BrE is more complex: while many UK publishers now prefer -ise, the Oxford University Press has historically defended -ize as etymologically correct for most verbs. The safest approach is to follow the specific journal or institution guidelines. When no guidance is given, use -ise for BrE and -ize for AmE, and apply the choice uniformly to every relevant word in the document.

Important: a subset of verbs ending in -ise cannot be spelled -ize in any variety of English, because they derive from roots other than the Greek -izein. These words are fixed:

• advertise, advise, arise, compromise, devise, disguise, enterprise, exercise, franchise, improvise, merchandise, premise, revise, supervise, surmise, surprise, televise

Spelling in Scientific Vocabulary

Scientific terminology inherits many spelling differences from the general patterns above, but some additional considerations apply specifically in research contexts.

Field	British Term	American Term
Medicine / Biology	haemoglobin, oedema, diarrhoea, anaesthetic	hemoglobin, edema, diarrhea, anesthetic
Medicine / Biology	aetiology, paediatrician, gynaecology	etiology, pediatrician, gynecology
Chemistry / Biochemistry	sulphur, aluminium, manoeuvre	sulfur, aluminum, maneuver
Chemistry / Biochemistry	adrenocorticotrophic, gonadotrophin	adrenocorticotropic, gonadotropin
General science	artefact, programme (non-computer)	artifact, program
General science	draught (fluid flow), mould, plough	draft, mold, plow

Common Academic Verbs: A Quick Reference

American English	British English
Analyze	analyse
Categorize	categorise
Characterize	characterise
Emphasize	emphasise
Globalize	globalise
Hypothesize	hypothesise
Maximize	maximise
Minimize	minimise
Optimize	optimise
Prioritize	prioritise
Randomize	randomise
Recognize	recognise
Standardize	standardise
Synthesize	synthesise

Common Academic Nouns: A Quick Reference

American English	British English
Acknowledgment	acknowledgement
Artifact	artefact
Behavior	behaviour
Center	centre
Color	colour
Defense	defence
Enrolment	enrolment
Fiber	fibre
Fulfilment	fulfilment
Humor	humour
Judgment	judgement
Labor	labour
license (noun and verb)	licence (noun) / license (verb)
Liter	litre
Meter	metre
Neighbor	neighbour
Organization	organisation
Program	programme (non-computer)
Skeptical	sceptical
Theatre	theatre

Punctuation

Punctuation conventions in academic writing differ most sharply in three areas: the use of quotation marks, the placement of periods relative to quotation marks, and the use of the serial (Oxford) comma. Differences in how abbreviations are punctuated also apply, particularly for titles and Latin scholarly abbreviations.

Quotation Marks

Feature	American English	British English
Primary quotation marks	Double marks: “example”	Single marks: ‘example’
Quote within a quote	Single marks inside double: “she said ‘yes'”	Double marks inside single: ‘she said “yes”‘
Period / full stop placement	Always inside the closing quotation mark	Outside unless the punctuation belongs to the quoted text
Comma placement	Always inside the closing quotation mark	Outside unless the comma belongs to the quoted text

Examples in academic prose:

• AmE: The author described this as “a critical oversight in the literature.”
• BrE: The author described this as ‘a critical oversight in the literature’.
• AmE (quote within quote): The reviewer noted “the author’s reliance on ‘outdated methodology’ is problematic.”
• BrE (quote within quote): The reviewer noted ‘the author’s reliance on “outdated methodology” is problematic’.

The Oxford Comma (Serial Comma)

AmE strongly favors using a comma before the final item in a list of three or more elements (the Oxford comma). BrE treats the Oxford comma as optional and frequently omits it. In academic writing, the Oxford comma is recommended in both varieties when its omission could cause ambiguity.

• AmE (with Oxford comma): The study examined motivation, engagement, and performance.
• BrE (often without): The study examined motivation, engagement and performance.
• Ambiguous without Oxford comma: The paper was dedicated to her supervisors, Freud and Jung. (Without the Oxford comma, it reads as if Freud and Jung are the supervisors.)

Abbreviations and Periods

Abbreviation type	American English	British English
Title abbreviations (truncated)	Dr., Mr., Mrs., Prof., St.	Dr, Mr, Mrs, Prof, St (no period if last letter of abbreviation matches last letter of full word)
Title abbreviations (contracted)	Hon. (Honorable)	Hon. (Honourable, since abbreviation does not end on last letter)
Latin scholarly terms (e.g., i.e.)	Comma follows: e.g., i.e.,	No comma follows: e.g. i.e.
Etc.	etc. (with period)	etc. (with period, same in both)

Capitalization After a Colon

A subtle but frequently encountered difference relates to capitalization after a colon. In AmE, if a full, independent sentence follows a colon, its first word is typically capitalized. In BrE, it is not.

• AmE: The results confirm one thing: The intervention was effective.
• BrE: The results confirm one thing: the intervention was effective.

Grammar and Verb Usage

Grammatical differences between BrE and AmE are fewer and more subtle than spelling differences, but they are consequential in formal academic prose. The most important areas involve collective noun agreement, the choice between present perfect and simple past tense, and a small number of preposition and auxiliary verb preferences.

Do Collective Nouns Take Singular or Plural Verbs?

Yes, in AmE they nearly always take singular verbs. Collective nouns, words that name a group as a single unit, behave differently across the two varieties. This affects research writing whenever discussing teams, committees, populations, or organizations.

Context	American English	British English
Group treated as a unit	The research team was provided with equal funding.	The research team was provided with equal funding.
Group acting as individuals	The research team was unable to reach consensus.	The research team were unable to reach consensus.
Other examples	The committee has decided. The government is planning.	The committee have decided. The government are planning.

An AmE author who wants to emphasize individuals within a group can rewrite: “Members of the research team were unable to reach consensus.” This avoids the plural verb without ambiguity.

Present Perfect vs. Simple Past

BrE prefers the present perfect tense in contexts where an action has just occurred or directly affects the current moment, often with the adverbs just, already, and yet. AmE commonly uses the simple past in these same contexts.

Situation	British English (present perfect preferred)	American English (simple past acceptable)
Recent discovery	The authors have just published the findings.	The authors just published the findings.
Completed action affecting now	The data have already been analyzed.	The data were already analyzed.
Negation with “yet”	The limitations have not yet been addressed.	The limitations were not yet addressed.

Note: In formal academic writing, BrE authors often use the present perfect even when AmE authors might not find it strictly necessary. Either choice is acceptable if applied consistently within the chosen variety.

Irregular Past Tenses

BrE permits, and in some registers prefers, irregular past tense forms that AmE has largely replaced with regular -ed endings. Both forms are correct within the respective variety; mixing them is the problem.

Base verb	American English (past)	British English (past)
burn	burned	burned / burnt
dream	dreamed	dreamed / dreamt
kneel	kneeled	kneeled / knelt
learn	learned	learned / learnt
smell	smelled	smelled / smelt
spell	spelled	spelled / spelt
spill	spilled	spilled / spilt

Prepositions and Minor Grammatical Differences

Feature	American English	British English
At / on the weekend	on the weekend	at the weekend
In / on a street	on Elm Street	in Elm Street
Different from / to / than	different from (preferred), different than (common)	different from (preferred), different to (also common)
Auxiliary: “have got”	have (preferred): “Do you have the data?”	have got (common): “Have you got the data?”
“Shall” for future	Rarely used; “will” used almost exclusively	More common, especially in first-person formal prose

Dates, Numbers, and Formatting

Date format is one of the most practically important differences for academic writers because it can cause genuine confusion: the date 06/07/2024 means 6 July in BrE and July 6 in AmE. Adopting an unambiguous format, particularly in methods sections and data tables, eliminates the risk entirely.

Date Formats

Format	British English	American English
Verbal (formal)	20 October 2024 / 20th October 2024	October 20, 2024
Numerical (DD/MM/YYYY vs. MM/DD/YYYY)	20/10/2024	10/20/2024
ISO 8601 (recommended for academic use to avoid ambiguity)	2024-10-20	2024-10-20
Ordinal use	“the 20th of October” is common	Ordinals in dates are uncommon

Best practice in academic writing: use the full verbal format (e.g., 20 October 2024 or October 20, 2024) or ISO 8601 (2024-10-20) in methods sections and appendices to prevent misreading by international readers.

Numbers, Decimals, and Thousands Separators

Feature	American English	British English
Decimal mark	Period: 3.14	Period: 3.14 (same; comma is used in some European styles but not standard BrE)
Thousands separator	Comma: 1,000,000	Comma: 1,000,000 (same in formal BrE; thin space used in some scientific contexts)
Billion	1,000,000,000 (short scale)	1,000,000,000 (short scale now standard in both; older BrE used long scale = 1,000,000,000,000)

Vocabulary Differences in Academic and Scientific Contexts

Vocabulary divergence is the least systematic category of differences, and therefore the hardest to master by rule. The safest approach is to read recent issues of the target journal or examine sample theses from the target institution to develop a feel for the vocabulary conventions in use.

General Vocabulary Divergence

American English	British English	Notes for academic use
program	programme (non-computer)	“Computer program” is the same in both varieties
transportation	Transport	Common in engineering and policy studies
aluminum	Aluminium	The IUPAC name is “aluminium”
sulfur	Sulphur	IUPAC recommends “sulfur”
math	Maths	Use “mathematics” in formal writing; avoids the issue
counterclockwise	anti-clockwise	Technical descriptions of rotation
freshman / sophomore	first-year / second-year (student)	Year-based terms are preferred in international journals
cell phone / cellphone	mobile (phone)	Write “mobile phone” for maximum clarity
on the weekend	at the weekend	Preposition, not vocabulary, but listed here for ease

Medical and Scientific Vocabulary

American English	British English
anesthesia / anesthetic	anaesthesia / anaesthetic
Diarrhea	diarrhoea
Edema	oedema
Esophagus	oesophagus
Estrogen	oestrogen
Gynecology	gynaecology
haemorrhage / hemorrhage	haemorrhage
Leukemia	leukaemia
Maneuver	manoeuvre
Pediatrics	paediatrics

Note: Some terminology has been converging toward AmE in international journals, even those published in the UK. For example, “tumor necrosis factor” (AmE spelling) is the established gene and protein nomenclature used globally. Always check the specific journal’s author guidelines and its recently published articles before defaulting to the BrE spelling of a technical term.

The Practice vs. Practise Distinction

This pair represents a special case worth highlighting for academic writers. In BrE, “practice” (noun) and “practise” (verb) are spelled differently. In AmE, “practice” serves as both noun and verb.

• BrE: Researchers should practise rigorous methodology. Good practice requires reproducibility.
• AmE: Researchers should practice rigorous methodology. Good practice requires reproducibility.
• A similar noun/verb distinction applies in BrE to “licence” (noun) and “license” (verb). AmE uses “license” for both.

Style Guides and Their Language Conventions

Major academic style guides each specify a language variety and punctuation convention. When a journal or institution mandates a particular style guide, those specifications take precedence over a writer’s personal preference.

Which Style Guides Use Which Variety?

Style Guide	Language variety	Primary disciplines
APA (7th ed.)	American English	Social sciences, psychology, education, nursing
MLA (9th ed.)	American English (quotation rules follow BrE-like logic in some editions)	Humanities, literature, languages
Chicago / Turabian	American English (Notes-Bibliography) or flexible	Humanities, history, fine arts
Harvard (UK variant)	British English	Wide range; common in UK and Australian institutions
Vancouver / ICMJE	Flexible; journal-specific	Medicine, clinical sciences
IEEE	American English	Engineering, computer science, electronics
AMA	American English	Medicine, public health

Citation-Style-Specific Punctuation Rules

• APA: Periods and commas go inside quotation marks (AmE rule). Double quotation marks for all quotations. Oxford comma required in lists.
• MLA: The guide’s punctuation conventions align with AmE for quotation marks and placement. Oxford comma is used.
• Chicago (Notes-Bibliography): American punctuation conventions, including periods and commas inside quotation marks. Oxford comma is used.
• Harvard (UK variant): Follows BrE conventions, placing periods and commas outside quotation marks unless they are part of the original quotation.

Why Consistency Matters More Than Which Variety You Choose

In academic writing, the choice between BrE and AmE is generally less important than the consistent application of whichever variety is chosen. A manuscript that begins with “colour” and ends with “color,” or that uses “organise” and “organize” interchangeably, signals poor proofreading. Reviewers and examiners are trained to notice this, and it can lead to immediate return for revision, regardless of the quality of the research.

The Most Common Sources of Inconsistency

• Repurposing text across documents: A researcher who writes a thesis chapter in BrE and then incorporates it into a journal submission targeting an AmE journal must systematically convert all spellings, not just the obvious ones.
• Collaborative writing: When multiple authors contribute sections, each may default to their native variety, resulting in a patchwork document.
• Online sources and references: Quoting directly from a source written in a different variety can introduce inconsistent spellings into a manuscript. Quotations should be reproduced exactly as written, so the surrounding text must account for this.
• Spell-checker defaults: Many word processors default to AmE regardless of the user’s intended variety. Always confirm the proofing language setting before beginning to write.
• Scientific terminology: Some technical terms have established spellings that do not align with the author’s chosen variety (e.g., “tumor necrosis factor” is used globally regardless of BrE/AmE choice).

Practical Consistency Checklist

• Set the proofing language in Word before writing (Review > Language > Set Proofing Language).
• Create a personal word list or glossary of the 20 to 30 words in your field that differ most between BrE and AmE. Consult it before each proofing pass.
• Run a search for tell-tale pairs (color/colour, analyze/analyse, center/centre) using the Find function after completing a draft.
• If you use AI-assisted writing or grammar tools, verify that they are set to the correct language variety; many default to AmE.
• When quoting directly from sources in a different variety, note the spelling in your quotation log so you can verify it is unchanged in the final document.
• Have a human reader familiar with the target variety review the manuscript before submission (Editage’s professional editing services can help with this).

Choosing the Right Variety for Your Context

The correct choice of language variety for an academic document is rarely a matter of personal preference: it is usually determined by the institution, the journal, or the supervisor. The hierarchy below covers most situations.

Which Variety Should You Use?

Context	Recommended variety	How to confirm
Thesis or dissertation at a UK university	British English	Check the university’s thesis guidelines or ask the supervisor
Thesis or dissertation at a US university	American English	Check the graduate school formatting guide
Thesis at an Australian or Canadian institution	Follows BrE for Australia; mixed for Canada	Check institutional guidelines; Australian English is closer to BrE
Journal submission (journal specifies)	Follow author guidelines exactly	Read the journal’s “Instructions for Authors” page
Journal submission (journal does not specify)	Either, applied consistently	Check recently published articles in the journal to infer the norm
Conference paper	Follow conference guidelines; often AmE for international STEM conferences	Check the call for papers
No guidance given	Default to the variety most natural to you, applied consistently	Confirm with supervisor or editor before submission

Do Journals Favor One Variety Over the Other?

In practice, AmE is more prevalent in international peer-reviewed journals, particularly in the natural sciences, medicine, engineering, and computer science. Many major publishers, including Elsevier, Wiley, Springer Nature, and the American Chemical Society, publish predominantly in AmE or accept either variety with equal standing. The New England Journal of Medicine, JAMA, and IEEE all require AmE. The BMJ, though British, accepts both varieties and its author guidelines note a preference for US spelling as the internationally recognized norm. European journals and humanities journals are more likely to accept or require BrE.

Considerations for Non-Native English Speakers

Non-native speakers face a particular challenge: their training in English may have emphasized one variety, but the target journal or institution may require the other. Additional difficulties arise because online resources, dictionaries, and AI writing tools often mix varieties or default to AmE.

Common Challenges for Non-Native Writers

• Defaulting to whichever variety appears in online grammar resources, which are often AmE-centric.
• Learning British spellings in school (common outside the US) and then submitting to AmE journals.
• Using spell-checking tools set to the wrong variety without realizing it.
• Copying text from web sources, review papers, or textbooks that may use a different variety than the target journal.
• Being unfamiliar with the grammar differences (collective nouns, present perfect) that do not affect spelling and are therefore not caught by spell-checkers.

Practical Strategies

• Before beginning any document, identify the target variety and set the word processor proofing language accordingly.
• Use a dedicated BrE or AmE dictionary (Oxford for BrE, Merriam-Webster for AmE) as the authoritative reference for any word that the spell-checker does not flag.
• When in doubt about a specific term, search for it in recently published articles in the target journal and use the spelling found there.
• For thesis work, ask the supervisor early, and keep a copy of any written guidance they provide about language variety.
• Do a focused search-and-replace pass for the 10 to 15 pairs most likely to have been mixed, using the list in this guide, before any final submission.
• Professional proofreading by a native speaker of the target variety is strongly recommended, especially for doctoral theses and manuscripts targeting high-impact journals.

International Readability and Clarity

Global scholarship increasingly demands that academic writing be intelligible to readers from many linguistic backgrounds. When a term differs substantially between varieties, or when a region-specific expression could cause confusion, clarity should take precedence over strict regional conformity.

• When introducing a highly region-specific term for the first time, consider providing a parenthetical alternative: “petrol (gasoline)” or “mobile phone (cell phone).”
• Sports-based idioms and cultural expressions can be opaque across varieties. BrE “playing with a straight bat” and AmE “Monday-morning quarterback” are each meaningful within their cultures but confusing outside them. Avoid such idioms in formal academic writing.
• The word “billion” historically meant different values in BrE (one million million) and AmE (one thousand million). Modern BrE has adopted the AmE “short scale,” but international readers from countries using European numbering conventions may still be confused. Write out the numerical value explicitly: “1,000,000,000 (one billion, short scale)” if there is any possibility of ambiguity.
• Some technical terms have converged on a single international spelling through standards bodies such as IUPAC (International Union of Pure and Applied Chemistry) or the IUPHAR nomenclature authority. These standardized spellings take precedence over either BrE or AmE in their respective fields.

Frequently Asked Questions

My university has no stated preference for BrE or AmE. Does it matter which I use?

It matters only insofar as you must choose one and apply it consistently. In the absence of institutional guidance, ask your supervisor directly before beginning. Most supervisors care more about consistency than about which variety is chosen, but some have personal or departmental preferences. Getting a clear answer early prevents the need for wholesale revision at submission.

Can I mix BrE and AmE if my topic involves both UK and US contexts?

No. The subject matter of your research does not change the language variety requirement. If your paper compares UK and US public policy, you still write the manuscript in a single variety throughout. Technical terms from the other variety can be introduced in quotation marks or with a parenthetical note, but the prose itself should remain consistent.

I am a non-native speaker writing in English. Which variety is easier to learn for academic writing?

Neither is inherently simpler. AmE is more prevalent in international scientific journals and in many online grammar resources, which can make it easier to find reference material. BrE is more common in European and Australian institutions. The practical answer is to learn whichever variety is required by your immediate context, whether that is your institution’s thesis guidelines or your target journal’s author instructions.

I wrote my thesis in BrE and am now submitting to an AmE journal. What is the fastest way to convert?

The most efficient approach combines a search-and-replace pass for the highest-frequency differences with a dedicated proofreading round. Start with the patterns most likely to be missed: -ise/-ize verbs, -our/-or nouns, -re/-er nouns, doubled consonants (labelled/labeled), and the ae/oe ligature words. After the automated pass, read the document specifically for grammar differences (collective noun agreement, present perfect vs. simple past) that spell-checkers cannot detect.

My supervisor uses different spellings than the ones my word processor flags. Who is right?

Supervisors take priority in institutional contexts, per most university guidelines. If your supervisor explicitly instructs you to use a particular spelling or variety, follow that instruction even if it conflicts with what your word processor flags. Note the instruction in writing for your own records. After completing the degree, the author guidelines of the target journal then take priority over personal preference.

Does it matter whether I use the Oxford comma in an AmE academic paper?

In most AmE academic contexts, particularly when following APA, Chicago, or MLA style, the Oxford comma is standard and expected. Omitting it in a clearly AmE document can appear inconsistent. More importantly, the Oxford comma prevents genuine ambiguity in some sentences. When in doubt, include it: it is never wrong in AmE academic writing.

Are there any words that look like BrE/AmE differences but are actually the same in both?

Yes, several pairs confuse writers. “Aerofoil” and “anaerobic” use “ae” but are spelled the same in both varieties. Words like “install,” “compel,” and “excel” do not double the final consonant before a suffix in either variety. The suffix -ise in words such as “advise,” “comprise,” “supervise,” and “surprise” is fixed in both AmE and BrE and cannot become -ize. Words like “parallel” and “travel” follow a pattern where the stem-final l is doubled in BrE but not AmE, yet “install” and “excel” do not follow this rule in either variety.

Will a journal actually reject my paper just because I mixed BrE and AmE?

Outright rejection on language grounds alone is uncommon at the first-round review stage, but editors may return a manuscript before peer review if the language quality is judged insufficient. Mixed varieties are one marker editors use to assess the overall linguistic care taken with a submission. More commonly, reviewers will note language inconsistency in their feedback, which can delay acceptance. Consistent, clean language variety signals professionalism and thoroughness, qualities that carry weight in peer review.