Promise vs Vow

When to use each in English, with meaning, register, and examples.

Promise

Top 1,000 (very common)A2verb

Vow

FormalTop 3,000 (common)C1verb
Most formal: VowMost common: Promise
 PromiseVow
Pronunciation🇬🇧 /["/ˈprɒmɪs/","/ˈprɒmɪsɪz/","/ˈprɒmɪst/","/ˈprɒmɪsɪŋ/"]/🇺🇸 /["/ˈprɑːmɪs/","/ˈprɑːmɪsɪz/","/ˈprɑːmɪst/","/ˈprɑːmɪsɪŋ/"]/🇬🇧 /["/vaʊ/","/vaʊz/","/vaʊd/","/ˈvaʊɪŋ/"]/🇺🇸 /["/vaʊ/","/vaʊz/","/vaʊd/","/ˈvaʊɪŋ/"]/
MeaningA commitment to do something or not do something.A serious promise to do something.
ExampleI promise to help you with your homework.She vowed never to speak to him again.
RegisterNeutralFormal
How commonTop 1,000 (very common)Top 3,000 (common)
CEFR levelA2C1
Part of speechverbverb
Collocationsfaithfully, solemnly, initially, can, cannot, seem to, to, as promised, I can’t promise anythingquietly, silently, to, vow never to do something, vow revenge, vow revenge against somebody
Antonymslie, break, betraybreak, violate
Common mistakesConfusing 'promise' with 'vow' or 'pledge' in terms of strength., Using 'promise' without an object (e.g., 'I promise' should specify what)., Misusing in the past tense (e.g., 'I promised' without a follow-up).Confused with 'cow' — they sound similar but have different meanings., Using in informal contexts — 'vow' is too strong for casual promises.
Usage notesUse 'promise' when you want to express a vow or assurance. Common in both spoken and written contexts, but avoid in formal legal documents.Use 'vow' when making a serious commitment, often in formal situations like weddings or ceremonies. Avoid in casual conversations.

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Promise

Frequently asked questions: Promise vs Vow

What's the difference between Promise and Vow?

Promise: A commitment to do something or not do something. Vow: A serious promise to do something.

Which is more formal: Promise and Vow?

Vow is the most formal of these.

Which is more common: Promise and Vow?

Promise is the most common in everyday English.

Which is more advanced: Promise and Vow?

Vow is the highest level, at C1, on the CEFR scale.

Are Promise and Vow the same CEFR level?

Promise: A2, Vow: C1 on the CEFR scale.

What part of speech are Promise and Vow?

Promise: verb, Vow: verb.

Can you show an example of each?

Promise: I promise to help you with your homework. Vow: She vowed never to speak to him again.

Can I use Promise and Vow interchangeably?

Not always. Promise and Vow are related and overlap in some contexts, but they differ in register, how common they are, and usage, so swapping one for another can change the meaning or tone. Check the differences above before substituting.

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