# Boyle's Law Calculator

Free Boyle's Law calculator. Calculate pressure or volume changes for gases at constant temperature using P1V1 = P2V2.

## What this calculates

Calculate pressure or volume of a gas using Boyle's Law: P₁V₁ = P₂V₂. This law states that at constant temperature, the pressure and volume of a gas are inversely proportional.

## Inputs

- **Solve For** — options: P₁ (Initial Pressure), V₁ (Initial Volume), P₂ (Final Pressure), V₂ (Final Volume) — Select which variable to calculate.
- **P₁ (Initial Pressure)** (atm) — min 0 — Initial pressure of the gas.
- **V₁ (Initial Volume)** (L) — min 0 — Initial volume of the gas.
- **P₂ (Final Pressure)** (atm) — min 0 — Final pressure of the gas.
- **V₂ (Final Volume)** (L) — min 0 — Final volume of the gas.

## Outputs

- **Result** — The calculated value.
- **Unit** — formatted as text — The unit of the result.
- **Formula** — formatted as text — Step-by-step calculation.

## Frequently Asked Questions

**Q: What is Boyle's Law?**

A: Boyle's Law states that for a fixed amount of gas at constant temperature, the pressure is inversely proportional to the volume. Mathematically: P₁V₁ = P₂V₂. If you compress a gas (decrease volume), the pressure increases.

**Q: When does Boyle's Law apply?**

A: Boyle's Law applies to ideal gases at constant temperature (isothermal process) with a fixed amount of gas. Real gases approximate this behavior at low pressures and high temperatures.

**Q: What units should I use?**

A: Any pressure and volume units work as long as you are consistent. P₁ and P₂ must use the same unit, and V₁ and V₂ must use the same unit. Common choices are atm with liters, or kPa with liters.

**Q: What is the relationship between Boyle's Law and the Ideal Gas Law?**

A: Boyle's Law is a special case of the Ideal Gas Law (PV = nRT). When n (moles) and T (temperature) are constant, PV = constant, which gives P₁V₁ = P₂V₂.

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Source: https://vastcalc.com/calculators/chemistry/boyles-law
Category: Chemistry
Last updated: 2026-04-21