Boyle's Law Calculator (Pressure–Volume)
Use Boyle's law P₁V₁ = P₂V₂ to find a gas's new pressure or volume at constant temperature.
How it works
P₁ · V₁ = P₂ · V₂ · P₂ = (P₁ · V₁) ÷ V₂ (constant temperature and amount of gas)
Boyle's law says that for a fixed amount of gas at constant temperature, pressure and volume are inversely proportional: squeeze the volume and the pressure rises in exact proportion, so the product P·V stays constant. Rearranging the relation gives the final pressure after a volume change. Any consistent units work because only the ratio matters.
Worked example
A gas at 1 atm filling 4 L, compressed to 2 L at the same temperature, reaches P₂ = (1 × 4) ÷ 2 = 2 atm — halving the volume doubles the pressure.
Sources: Boyle's law — Wikipedia
Frequently asked questions
What has to stay constant?
Temperature and the amount of gas. Boyle's law isolates the pressure–volume relationship, so it holds only when the gas is neither heated nor cooled and none is added or removed.
What does inversely proportional mean here?
As one quantity goes up, the other goes down by the same factor, keeping their product fixed. Double the pressure and the volume halves; triple the volume and the pressure falls to a third.
How is this different from the combined gas law?
Boyle's law fixes temperature and varies only pressure and volume. When temperature changes too, you need Charles's law or the combined gas law, P₁V₁/T₁ = P₂V₂/T₂.
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Educational estimate. Check the formula, units and significant figures for your exact case.