# Molar gas volume

One mole of any gas takes up 24 dm3 at room temperature and pressure. This lets you convert between moles of a gas and its volume.

Chemistry (school) · Part 05: Moles and calculations · Card 9 of 9 · Last updated 2026-10-19

## Analogy

Like every bus having the same number of seats: one mole of gas always fills the same space.

## Example

**Gas volume**

Volume = moles x 24 dm3
0.25 mol x 24
= 6 dm3

## In practice

0.5 mol of hydrogen gas has a volume of 12 dm3.

## Practice

### Flashcards

- **What is the volume of one mole of any gas at room temperature and pressure?** 24 dm3.

## Questions people ask

### Does the 24 dm3 value work for every gas?

Yes, at room temperature and pressure, which is about 20 degrees Celsius and 1 atmosphere. One mole of hydrogen, oxygen or carbon dioxide each fills 24 dm3. Gas particles are far apart, so their size does not matter, only how many there are.

### How do you find the volume of gas made in a reaction?

Work out the moles of the gas using the balanced equation. Then multiply by 24 dm3 per mole. If 0.1 mol of hydrogen is made when zinc reacts with acid, the volume is 0.1 x 24 = 2.4 dm3, which is 2,400 cm3.

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