Fully vs One hundred percent

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

Fully

Top 2,000 (common)B2adverb

One hundred percent

Top 2,000 (common)
 FullyOne hundred percent
Pronunciation🇬🇧 /["/ˈfʊli/"]/🇺🇸 /["/ˈfʊli/"]/🇬🇧 //wʌn ˈhʌndrəd pəˈsɛnt//🇺🇸 //wʌn ˈhʌndrəd pərˈsɛnt//
Meaningcompletely or totallyCompletely or totally.
ExampleI **fully understand** your motives.I am one hundred percent sure about my decision.
RegisterNeutralNeutral
How commonTop 2,000 (common)Top 2,000 (common)
CEFR levelB2-
Part of speechadverb
Collocationsfully aware, fully prepared, fully understand, fully loaded, fully engageone hundred percent accurate, one hundred percent engaged, one hundred percent committed
Antonymspartially, incompletely, slightly-
Common mistakesUsing 'fully' in place of 'very' which is not always correct., Confusing 'fully' with 'fill' in terms of spelling., 'Fully' is sometimes misused in contexts where 'entirely' or 'completely' fit better.Using 'one hundred percent' without context, leading to confusion., Confusing with 'a hundred percent' which has the same meaning., Overusing in formal writing where simpler phrases would suffice.
Usage notesUse 'fully' to emphasize that something is done to the highest degree. Avoid using it in very casual speech where simpler words like 'really' may be preferred.Use in both speaking and writing to express totality or full agreement. Generally appropriate in any informal or formal context.

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One hundred percent

Frequently asked questions: Fully vs One hundred percent

What's the difference between Fully and One hundred percent?

Fully: completely or totally One hundred percent: Completely or totally.

Can you show an example of each?

Fully: I **fully understand** your motives. One hundred percent: I am one hundred percent sure about my decision.

Can I use Fully and One hundred percent interchangeably?

Not always. Fully and One hundred percent 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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