How major style guides rule on "percent"
American guides write 'percent' as one word; British 'per cent' is two. APA 7 uses the % symbol with numerals.
The disagreement on "percent" is an example of systematic American vs British English differences, the category of style-guide differences that most often confuses copy editors and creates inconsistency across long documents. Below is a guide-by-guide breakdown, drawn directly from the published editions cited.
| Style guide | Preferred form |
|---|---|
| AP Stylebook (2024–2025 Edition) | percent |
| Chicago Manual of Style | percent |
| MLA Handbook | percent |
| APA Publication Manual | percent (use % with numerals) |
| Merriam-Webster Dictionary | percent |
What the divergence actually means
Unlike many compound-modernization decisions where style guides eventually converge, "percent" continues to show genuine divergence between major guides. The AP Stylebook treats this as a settled call; Chicago Manual leaves more flexibility; and Merriam-Webster, as a descriptive dictionary, records both forms. Source: Chicago Manual of Style, 17th Edition
The APA Publication Manual diverges here: it specifies "percent (use % with numerals)" as the form preferred for academic writing in psychology and behavioral-science journals. APA's reasoning typically tracks scientific publishing conventions rather than newspaper-style economy. Source: APA Publication Manual, 7th Edition
Merriam-Webster lists "percent", which serves as the lexicographic baseline for U.S. style decisions. Because Merriam-Webster's entries reflect aggregated published usage rather than editorial preference, when a guide says "follow Merriam-Webster", as APA does, that effectively delegates the call to whichever spelling has dominated the published corpus. Source: Merriam-Webster Dictionary
Garner's Modern English Usage classifies the "percent" / "per cent" pair on its Language-Change Index, a five-stage scale measuring whether a once-disputed form has been accepted into Standard English. For systematic American vs British English differences, Garner's typically rates the dominant form at Stage 4 ("ubiquitous but objected to by traditionalists") or Stage 5 ("fully accepted"). Source: Garner's Modern English Usage, 5th Edition
Practical guidance for editors
For working writers, the practical rule is straightforward: in journalism, follow AP; in academic writing in the humanities, follow MLA or Chicago; in social-science publishing, follow APA; in book publishing, follow Chicago. When no house style applies, Merriam-Webster's main entry is the safest default. The differences across these guides on "percent" reflect not disagreement about correctness but different audiences and editorial pressures.
Editorial context
Google Books Ngrams data for American English shows "percent" surpassing "per cent" around 1920, marking a tipping point after decades of gradual compounding that aligned with U.S. editorial pushes for streamlined typography in newspapers and government manuals. By 1950, "percent" appeared over ten times more frequently than its rival in U.S. publications, a lead widening to 50:1 by the 2000s, while "per cent" held firm as the majority form in British English corpora through the present. This corpus evidence highlights typesetting legacies, "per cent" as a holdover from 18th-century adverbial phrases like "by the cent", persisting against American efficiency drives that favored one-word forms to save column inches. Consider a business dispatch: Inflation eased to 2 percent last quarter, where the fused spelling aids scannability in data-heavy prose without sacrificing clarity.
Cross-references
For the dictionary entry, frequency data, and pronunciation of percent, see the main word page. For other style-guide spelling decisions in this category, browse all style-guide spelling rulings.