# Boyle’s Law Calculator

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

> The Boyle's law calculator finds the final pressure or volume of a gas compressed or expanded at constant temperature.

## Inputs

- Find
- Initial pressure p₁ (kPa, Pa, bar, atm, psi, MPa)
- Initial volume V₁ (L, m³, mL, ft³)
- Final volume V₂ (L, m³, mL, ft³)
- Final pressure p₂ (kPa, Pa, bar, atm, psi, MPa)

## Results

- Final pressure p₂
- Final volume V₂

## Formula

```
p₁·V₁ = p₂·V₂
```

## Explanation

Squeeze a gas into half the volume and its pressure doubles – as long as the temperature stays the same. Robert Boyle discovered this in 1662; it explains syringes, breathing and why divers' lungs must equalise.

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

- **Find**
- **Initial pressure p₁**
- **Initial volume V₁**
- **Final volume V₂**
- **Final pressure p₂**

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 other three values.

### Tips

- Use absolute temperature (K) in gas laws and efficiency formulas.
- Temperature differences are the same in K and °C.
- Heat = mass × specific heat × temperature change when no phase change occurs.
- Phase changes need latent heat at a constant temperature.

### Common mistakes to avoid

- Using °C in pV = nRT.
- Forgetting latent heat during melting or boiling.
- Confusing heat capacity (J/K) with specific heat (J/(kg·K)).

### Inputs explained

FieldWhat to enterFindChoose one: Final pressure p₂, Final volume V₂Initial pressure p₁Units: kPa, Pa, bar, atm, psi, MPaInitial volume V₁Units: L, m³, mL, ft³Final volume V₂Units: L, m³, mL, ft³Final pressure p₂Units: kPa, Pa, bar, atm, psi, MPa

### What each result means

- **Final pressure p₂** = [Initial pressure p₁]×[Initial volume V₁]÷[Final volume V₂]
- **Final volume V₂** = [Initial pressure p₁]×[Initial volume V₁]÷[Final pressure p₂]

### Example values

How the main result changes when **Initial pressure p₁** changes and everything else stays at the example values above:

Initial pressure p₁ (kPa)Final pressure p₂ (kPa)50.66101.32575.99151.9875101.33202.65126.66253.3125151.99303.975202.65405.3

## Worked example

Inputs — Find: Final pressure p₂; Initial pressure p₁: 101.325 kPa; Initial volume V₁: 10 L; Final volume V₂: 5 L.

Results — **Final pressure p₂ = 202.65 kPa**.

## Key terms

- **Isothermal**: At constant temperature.

## FAQ

**Does Boyle's law need constant temperature?**
Yes – it describes isothermal changes.

**Why do bubbles grow as they rise in water?**
Pressure decreases, so their volume increases.

**Are pressures absolute?**
Yes – use absolute, not gauge, pressure.

**Does it apply to real gases?**
Well at low pressures; deviations appear at high pressures.

**What formula does the Boyle's Law Calculator use?**
p₁·V₁ = p₂·V₂.


## Sources

- [OpenStax – Chemistry 2e](https://openstax.org/details/books/chemistry-2e)
- [OpenStax – University Physics Volume 2](https://openstax.org/details/books/university-physics-volume-2)
- [HyperPhysics (Georgia State University)](http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html)