percent: Style Guide Spelling Decisions (AP, Chicago, MLA, APA)

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.

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

Only one of these forms is frequent enough to carry a rank in our corpus: "percent", at #974. "per cent" appears in the dictionary data but not in the frequency sample, which is itself a signal about how rarely it turns up in running text. Source: PlainSpell corpus, Wiktionary (kaikki.org) headwords with FrequencyWords 2018 English ranks

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.

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.