adjective

inversely proportional

in-VURS-lee pruh-POR-shuh-nuhl

Inversely proportional (adjective) means Related in such a way that when one quantity increases, the other decreases by the same factor, so that multiplying the two together always gives the same number. Example: “At a fixed temperature, the pressure of a gas is inversely proportional to its volume.”

adjective

Related in such a way that when one quantity increases, the other decreases by the same factor, so that multiplying the two together always gives the same number.

"At a fixed temperature, the pressure of a gas is inversely proportional to its volume."

"Speed is inversely proportional to the time taken to cover a fixed distance."

informal Loosely, moving in opposite directions: as one thing goes up the other goes down.

"His enthusiasm for the project seemed inversely proportional to the amount of paperwork involved."

How to use inversely proportional

Learner’s notes

In plain EnglishWhen one goes up, the other goes down by the same factor.

When to use it

Technical in maths and science; used loosely and jokingly in everyday speech.

Memory tip

Test it by multiplying: if x times y stays the same for every pair, the relationship really is inverse.

Trace the full origin ↓

Easily confused with

directly proportional inverse vs negative correlation

Common pairings

inversely proportional to varies inversely inverse proportion inversely proportional relationship

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Fill the gap

Can you complete this real example?

At a fixed temperature, the pressure of a gas is _____ to its volume.

Etymology

From Latin inversus 'turned upside down' plus proportio 'a share or relation'.

Origin: Latin

Antonyms

directly proportional

Rhymes for inversely proportional

coronal rational diagonal personal seasonal national optional regional hormonal fictional emotional irrational

See all rhymes for inversely proportional →

Frequently asked questions

What is the difference between inversely proportional and directly proportional?

If two quantities are directly proportional, they rise and fall together and their ratio y divided by x stays constant. If they are inversely proportional, one falls as the other rises and their product x times y stays constant. Directly proportional graphs are straight lines through the origin; inversely proportional ones are curves called hyperbolas.

How do you write inversely proportional as a formula?

You write y is proportional to 1 over x, which becomes the equation y equals k divided by x, where k is a constant. Rearranged, that means x times y equals k for every pair of values.

Does inversely proportional just mean one goes up when the other goes down?

Not in maths. That looser idea is a negative or inverse relationship. True inverse proportion is stricter: doubling one quantity must exactly halve the other.

What is the meaning of inversely proportional?

"inversely proportional" (adjective) means related in such a way that when one quantity increases, the other decreases by the same factor, so that multiplying the two together always gives the same number.