Boyle's Law Calculator

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.

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.

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.

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.

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.