English UsageGrammar guide
Plural of Formula
Both “formulas” and “formulae” are accepted plurals of “formula.” Do not present “formulae” as the only correct plural or treat “formulas” as an error: both are dictionary-recorded forms.
Both “formulas” and “formulae” are accepted plurals of “formula.”
Key details
Confusion Familycompeting plural forms
Rule Familynumber and classical plurals
Termsformula, formulas, formulae
Variant ScopeMajor dictionaries record both “formulas” and “formulae” as plurals of “formula.”
Further guidance
Core difference
Both “formulas” and “formulae” are accepted plurals of “formula.”
Fast Test
Use the form expected by the field, publication, or house style; otherwise keep the choice consistent within a document.
Usage Boundary
Do not present “formulae” as the only correct plural or treat “formulas” as an error: both are dictionary-recorded forms.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- Formula — Merriam-Webster (opens in a new tab)Merriam-Webster · Dictionary evidence recording both formulas and formulae as plurals of formula.