Boyle's Law states that at constant temperature, the pressure and volume of a fixed amount of ideal gas are inversely proportional. Mathematically: P1 × V1 = P2 × V2, where the subscripts 1 and 2 refer to the initial and final states of the gas.

What conditions must hold for this law to apply?

Boyle's Law applies to ideal gases under two conditions: the temperature must remain constant (isothermal process) and the amount of gas must not change. Real gases approximate ideal behavior at low pressures and high temperatures.

Which units can I use for pressure and volume?

This calculator accepts pressure in atm, kPa, mmHg (Torr), and psi, and volume in liters (L), milliliters (mL), and cubic centimeters (cm³). All values are converted to common units before solving, so you can mix units freely.

What happens if I leave more than one field blank?

The calculator requires exactly three known values to solve for one unknown. If you leave two or more fields empty, it will show an error asking you to fill in the missing values.

Can Boyle's Law be used for liquids?

No. Boyle's Law applies to gases only. Liquids are nearly incompressible, so their volume does not change significantly with pressure under normal conditions.

Why does my result differ from a textbook answer?

Make sure your units match or that you are using the unit conversion options correctly. Also verify that the temperature and amount of gas are truly constant in your scenario — if either changes, you need the combined gas law or ideal gas law instead.

Boyle's Law Calculator

Enter any three of P1, V1, P2, V2 and instantly solve for the missing variable using Boyle's Law.

Enter Three Known Values

Leave exactly one field blank — that is the unknown to solve.

P₁ × V₁ = P₂ × V₂

Initial State

Initial Pressure (P₁)

Initial Volume (V₁)

Final State

Final Pressure (P₂)

Final Volume (V₂)

Fill in three values and click Calculate

Solved Variable

All Values Summary

Variable	Description	Value

Step-by-Step Solution

Summary

The Boyle's Law Calculator applies the relationship P1V1 = P2V2, which describes how the pressure and volume of a fixed amount of gas at constant temperature are inversely proportional. Enter any three of the four variables and the calculator instantly solves for the unknown. All calculations run client-side with no data sent to any server.

How it works

Enter values for three of the four variables: Initial Pressure (P1), Initial Volume (V1), Final Pressure (P2), or Final Volume (V2).
Leave exactly one field blank — that is the unknown the calculator will solve.
Select the appropriate unit for each pressure and volume field.
Click Calculate to apply the formula P1 × V1 = P2 × V2.
The result appears instantly with the solved value highlighted.
Click Reset to clear all fields and start a new calculation.

Use cases

Solve chemistry homework problems involving gas pressure and volume changes.
Predict the new volume of a gas when pressure increases in a syringe.
Calculate the pressure needed to compress a gas to a target volume.
Verify lab results by cross-checking measured pressure-volume pairs.
Understand the inverse relationship between pressure and volume for ideal gases.
Prepare for AP Chemistry or university-level gas law exams.
Model pneumatic systems where gas is compressed or expanded.
Convert between different pressure or volume units while solving gas law problems.

Frequently Asked Questions

Last updated: 2026-09-30 · Reviewed by Nham Vu