Meaning trap

build up

increase gradually

To make something become larger or greater over time, often slowly.

phrasal verbB1common

Don't mix these meanings

Same phrase, different job.

increase gradually

To make something become larger or greater over time, often slowly.

build up (develop strength or confidence)

Another meaning of 'build up' is 'develop strength or confidence'; compare the examples to keep the meanings separate.

Notice where the phrase sounds natural.

If you save a little money each month, your savings will build up over time.daily life
During the exam period, stress can build up if you don't take breaks.IELTS speaking

Pattern: build up (something) / build (something) up

WrongPressure builds up slowly over the time.

RightPressure builds up slowly over time.

'Over time' — no 'the'.

Patternbuild up (something) / build (something) up

Choose the version that sounds natural in speech.

Stiff A considerable accumulation of dust has gradually formed.

Natural Dust builds up if you don't clean.

'A considerable accumulation has gradually formed' is heavy; 'builds up' is natural.

Words that usually travel with it.

Not the same as 'increase suddenly' or 'explode'.

build up (develop strength or confidence) — Another meaning of 'build up' is 'develop strength or confidence'; compare the examples to keep the meanings separate.