Math
Boyle's Law Calculator
Apply Boyle's Law (P1V1 = P2V2) to a fixed amount of gas at constant temperature. Solve for any of P1, V1, P2, or V2 in atm, kPa, psi, mmHg, and more.
Boyle’s Law Calculator (P₁V₁ = P₂V₂)
Fill in any three of the four fields. Leave the unknown field empty and the calculator will solve for it.
Final volume (V₂)
1 L
P₁ (initial pressure)
1 atm
V₁ (initial volume)
2 L
P₂ (final pressure)
2 atm
V₂ (final volume)
1 L
Volume ratio V₂/V₁
0.5
Compression (gas was squeezed to 50% of its starting volume)
Solved volume in every unit
L
1
mL
1,000
m³
0.001
ft³
0.035315
gal (US)
0.264172
Boyle’s Law assumptions
Holds for a fixed amount of an ideal gas at constant temperature in a closed (sealed) container. If temperature changes, use the combined gas law. If the amount of gas changes, P₁V₁ = P₂V₂ no longer applies.
Frequently Asked Questions about the Boyle's Law Calculator
What is Boyle's Law?
Boyle's Law states that for a fixed amount of gas held at constant temperature, pressure and volume are inversely proportional. Expressed as P1 x V1 = P2 x V2, doubling the pressure on a sealed gas halves its volume, and halving the pressure doubles it. The law was published by Robert Boyle in 1662 and is the pressure-volume special case of the ideal gas law.
How does the calculator know which value to solve for?
Fill in any three of the four fields (P1, V1, P2, V2) with positive numbers and leave the unknown one empty. The calculator detects the blank field and applies the matching form of the equation. If zero or two or more fields are empty, no result is shown.
Do P1 and P2 have to use the same pressure unit?
Yes. All four entries use the pressure unit and the volume unit you pick at the top. Internally the calculator converts every value to SI (pascals and cubic meters) before doing the algebra, then converts back to your chosen units. It also shows the solved value in every supported pressure or volume unit, so you do not need to convert by hand.
What does the volume ratio V2/V1 tell me?
V2/V1 is the compression or expansion factor for the gas. A ratio less than 1 means the gas was compressed (its volume shrank); a ratio greater than 1 means it expanded. Because Boyle's Law is an inverse relationship, the pressure ratio P2/P1 is the reciprocal: if V2/V1 is 0.5, then P2/P1 is 2.
When does Boyle's Law stop working?
Boyle's Law assumes a fixed amount of ideal gas at constant temperature in a sealed container. It breaks down if temperature changes (use the combined gas law or Charles's Law), if the amount of gas changes, or at very high pressures and very low temperatures where real gases deviate from ideal behavior. For everyday pressure and temperature ranges with common gases, the approximation is excellent.