# fill up

CEFR B1 · Phrasal verb

Source: https://englishreference.com/word/fill-up
Updated: 2026-10-22

## Definition

to make something completely full. You use this when putting gas in a car or eating until you are full.

For teachers: To make a container or space completely full. It functions both transitively, taking a direct object, and intransitively to describe a space or container becoming occupied.

## Examples

- I need to fill up the car before our long trip.
- The waiter came around to fill up our water glasses several times during the meal.
- As the storm clouds gathered, the small reservoir began to fill up, eventually reaching its maximum capacity by midnight.

## Pitfalls

- Not "I need to fill up this application form." but "I need to fill out this application form." — 'Fill up' refers to physical volume, while 'fill out' or 'fill in' is used for documents.

## Usage notes

- This verb is often used transitively with a container or intransitively when a space becomes crowded.
- Teaching tip: Contrast with 'fill out' or 'fill in' to clarify that 'fill up' relates to physical volume or capacity.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.