# Avogadro’s Law Calculator

URL: https://speedycalculator.com/calculators/physics/avogadros-law/
Last updated: 2026-10-30

> The Avogadro's law calculator finds the final volume or amount of gas when the other changes at constant temperature and pressure.

## Inputs

- Find
- Initial volume V₁ (L, m³, mL, ft³)
- Initial amount n₁ (mol)
- Final amount n₂ (mol)
- Final volume V₂ (L, m³, mL, ft³)

## Results

- Final volume V₂
- Final amount n₂

## Formula

```
V₁/n₁ = V₂/n₂
```

## Explanation

Avogadro proposed in 1811 that equal volumes of gases at the same temperature and pressure contain equal numbers of molecules. So volume is proportional to the amount of gas – one mole of ideal gas fills about 22.4 L at 0 °C and 1 atm.

### How to use the Avogadro's Law Calculator

- **Find**
- **Initial volume V₁**
- **Initial amount n₁ (mol)**
- **Final amount n₂ (mol)**
- **Final volume V₂**

Results update as you type, every field has its own unit menu, and everything is calculated in your browser.

### How it works

Choose what to find and enter the initial volume and amount and the known final value.

### Inputs explained

FieldWhat to enterFindChoose one: Final volume V₂, Final amount n₂Initial volume V₁Units: L, m³, mL, ft³Initial amount n₁ (mol)A numberFinal amount n₂ (mol)A numberFinal volume V₂Units: L, m³, mL, ft³

### What each result means

- **Final volume V₂** = [Initial volume V₁]×[Final amount n₂ (mol)]÷[Initial amount n₁ (mol)]
- **Final amount n₂** = [Initial amount n₁ (mol)]×[Final volume V₂]÷[Initial volume V₁]

### Example values

How the main result changes when **Initial volume V₁** changes and everything else stays at the example values above:

Initial volume V₁ (L)Final volume V₂ (L)11.222.416.833.622.444.8285633.667.244.889.6

## Worked example

Inputs — Find: Final volume V₂; Initial volume V₁: 22.4 L; Initial amount n₁ (mol): 1; Final amount n₂ (mol): 2.

Results — **Final volume V₂ = 44.8 L**.

## Key terms

- **Mole**: 6.022 × 10²³ particles.

## FAQ

**What does Avogadro's law state?**
At constant T and p, gas volume is proportional to the number of moles.

**What is the molar volume?**
About 22.414 L/mol at 0 °C and 1 atm (STP).

**Does it work for real gases?**
Approximately, at moderate pressures.

**How does it relate to the ideal gas law?**
It is the n-dependence of pV = nRT.


## Sources

- [OpenStax – Chemistry 2e](https://openstax.org/details/books/chemistry-2e)
- [NIST – Fundamental physical constants](https://physics.nist.gov/cuu/Constants/)