“up to” is a multiword expression whose title-case result depends on both style and how that style treats the words inside a phrase. Treat the expression as a phrase span while still applying the chosen style’s rule to each component rather than treating the phrase as one indivisible token.
ReviewedEvidence6 sourcesSectionWriting & Style
Quick answer
APA: usually “Up to” when “up” is adverbial; Chicago requires the role of “up” to be known, so ambiguous cases stay left unresolved. MLA remains phrase/POS-aware.
Key details
Phraseup to
Rule Familymultiword-preposition-title-case
Termsup, to
Important caveats
Automation boundary
If the style requires unresolved grammatical or embedded-title analysis, leave the case unresolved rather than forcing an answer.
Phrase Boundary
Recognizing the phrase is useful, but phrase recognition alone does not override per-word style rules. Treat the expression as a phrase span, then apply the chosen style’s rule to each component.
Further guidance
Style Comparison
“Up” can be an adverb/particle or a preposition component, so spelling alone is not always enough for Chicago/MLA.
The reviewed rule set recognizes the span but does not lower its safety class merely because the words match a known phrase.
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.
APA title case capitalizes the first word, the first word of a subtitle, major words, and words of four letters or more while keeping short minor words lowercase in ordinary mid-title positions.
Chicago 18 uses title case for titles of works and changed a long-standing rule: prepositions of five letters or more are now capitalized. Shorter prepositions generally remain lowercase internally, while first and last words are capitalized and “to” remains lowercase as an infinitive marker in ordinary mid-title use.
MLA 9 describes title style as capitalizing the first word, last word, and all principal words. MLA’s public Style Center also documents the traditional lowercase treatment of internal prepositions, but its detailed preposition article is edition-labeled for MLA 8, so this engine does not yet treat the full MLA 9 converter profile as complete.
Prepositions are one of the clearest places where title styles diverge. APA uses a four-letter major-word threshold, Chicago 18 capitalizes prepositions of five letters or more, and MLA editorial guidance generally lowercases internal prepositions regardless of length.
“according to” is a multiword expression whose title-case result depends on both style and how that style treats the words inside a phrase. Treat the expression as a phrase span while still applying the chosen style’s rule to each component rather than treating the phrase as one indivisible token.
“due to” is a multiword expression whose title-case result depends on both style and how that style treats the words inside a phrase. Treat the expression as a phrase span while still applying the chosen style’s rule to each component rather than treating the phrase as one indivisible token.
“because of” is a multiword expression whose title-case result depends on both style and how that style treats the words inside a phrase. Treat the expression as a phrase span while still applying the chosen style’s rule to each component rather than treating the phrase as one indivisible token.
“instead of” is a multiword expression whose title-case result depends on both style and how that style treats the words inside a phrase. Treat the expression as a phrase span while still applying the chosen style’s rule to each component rather than treating the phrase as one indivisible token.
