English Reference

Phrasal verb

fill up

Irregular verb

Forms

Infinitive

fill up

Past

filled up

Past participle

filled up

Definition

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

phrasal verb. 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.”

Examples

simple

“I need to fill up the car before our long trip.”

contextual

“The waiter came around to fill up our water glasses several times during the meal.”

complex

“As the storm clouds gathered, the small reservoir began to fill up, eventually reaching its maximum capacity by midnight.”

Usage

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.

Pitfall

I need to fill up this application form.

I need to fill out this application form.

'Fill up' refers to physical volume, while 'fill out' or 'fill in' is used for documents.

Phrasal verb

Particles

up

Separability

optional

Pattern

fill + (object) + up

Synonyms

stuffsatiatereplenishtop up

Antonyms

emptydrain

Grammar

Phrasal verbs (introduction)

This entry

Exam level
CambridgeCambridgeCambridge English QualificationsThe exam suite from Cambridge University Press & Assessment, from A1 Movers up to C2 Proficiency. The benchmark names double as CEFR labels.B1 PreliminaryIELTSIELTSInternational English Language Testing SystemThe 0–9 band test co-owned by the British Council, IDP, and Cambridge. Used for university entry, work, and migration.4.0–5.0TOEFL iBTTOEFL iBTTest of English as a Foreign Language, Internet-Based TestETS's academic English test, the standard route for US university admissions. Scored 0–120, with a 1–6 scale since 2026.1–6 scale: 3.0–3.544–71TOEICTOEICTest of English for International CommunicationETS's workplace English test, big in Japan and Korea. Listening & Reading scores 10–990 and tops out at C1.550–784
Frequency
Common
Level
B1 · Intermediate
Updated

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