Boyle's Law Calculator - Pressure & Volume Solver
Use this Boyle's law calculator to solve pressure or volume from P1, V1, P2, and V2 with unit-aware gas law results.
Boyle's Law Calculator
Results
Assumes constant temperature, fixed gas amount, and absolute pressure.
What is a Boyle's Law Calculator?
A Boyle's law calculator solves the pressure-volume relationship for a fixed amount of gas at constant temperature. It is useful for chemistry homework, physics examples, syringe and cylinder problems, and quick pressure-volume checks.
- Find final pressure when gas volume changes.
- Find final volume when pressure changes.
- Convert mixed pressure and volume units before solving.
- Show the rearranged P1 x V1 = P2 x V2 formula.
For standalone pressure unit conversions, use our Pressure Converter.
Boyle's Law Formula
This Boyle's law formula calculator uses the standard inverse relationship between gas pressure and volume.
To solve for final pressure, use P2 = (P1 x V1) / V2. To solve for final volume, use V2 = (P1 x V1) / P2. Initial pressure and initial volume use the same rearrangement pattern.
ChemLibreTexts Boyle's Law describes the inverse relationship between pressure and volume when temperature and gas amount are constant.
For volume-only unit conversions, use our Volume Converter.
Key Concepts Explained
The Boyle's law pressure volume relationship is inverse: compressing a gas raises pressure, and expanding it lowers pressure, as long as the assumptions hold.
P1 and V1
Initial pressure and volume describe the gas before the change.
P2 and V2
Final pressure and volume describe the gas after compression or expansion.
Absolute pressure
Use pressure measured from vacuum. Gauge pressure needs atmosphere added first.
Constant temperature
Temperature must stay unchanged for this single gas-law relationship.
For density changes related to mass and volume, compare with our Density Calculator.
How to Use This Calculator
Choose the unknown
Select P1, V1, P2, or V2.
Enter values
Fill in the three known positive values.
Select units
Choose pressure and volume units for each field.
Review results
Check the solved value, formula, and base product.
If your problem changes temperature, use our Temperature Converter before choosing a broader gas law.
Benefits of Using This Calculator
- •Solve any variable: Find P1, V1, P2, or V2 without manual algebra.
- •Handle mixed units: Use one Boyle's law calculator with units for atm, psi, kPa, liters, gallons, and more.
- •Show the formula: The result panel displays the rearranged equation used.
- •Catch invalid inputs: Zero, negative, and missing known values are rejected.
For a broader chemistry tool that includes temperature and moles, use our Ideal Gas Calculator.
Factors That Affect Your Results
Constant temperature
When asking does temperature stay constant in Boyle's law, the answer is yes: this law assumes no temperature change.
Fixed gas amount
Leaks, added gas, or chemical reactions change the number of particles and break the simple equation.
Absolute pressure
Gauge pressure should be converted to absolute pressure before using P1 x V1 = P2 x V2.
Real gas behavior
Very high pressure or very low temperature can make gases deviate from ideal behavior.
OpenStax Chemistry 2e explains pressure, volume, amount, and temperature as linked gas variables in ideal gas models.
For heat and temperature-change calculations, compare with our Specific Heat Calculator.
Frequently Asked Questions (FAQ)
Q: What is Boyle's law?
A: Boyle's law says the pressure of a fixed amount of gas is inversely proportional to its volume when temperature stays constant.
Q: What is the Boyle's law formula?
A: The Boyle's law formula is P1 x V1 = P2 x V2, where P is absolute pressure and V is volume for the initial and final gas states.
Q: How do you calculate final pressure with Boyle's law?
A: Use P2 = (P1 x V1) / V2. Multiply initial pressure by initial volume, then divide by final volume.
Q: How do you calculate final volume with Boyle's law?
A: Use V2 = (P1 x V1) / P2. Multiply initial pressure by initial volume, then divide by final pressure.
Q: What units can I use in this Boyle's law calculator?
A: You can use Pa, kPa, bar, atm, psi, mmHg, and torr for pressure, plus L, mL, m3, cm3, ft3, and US gallons for volume.
Q: When does Boyle's law not apply?
A: Boyle's law does not apply well when temperature changes, gas is added or removed, pressure is gauge instead of absolute, or the gas is far from ideal behavior.