Calculate the final pressure and final volume of an isothermal reaction of gas using this Boyle’s law calculator. This calculator can evaluate all variables from the equation below given the other values are known.

Boyle’s Law Formula

The formula for Boyle’s law is as follows:

 p₁ * V₁ = p₂ * V₂ 
  • Where p1 and p2 are the initial and final pressures
  • V1 and V2 are the initial and final volumes
  • The reaction is iso-thermal

To calculate the initial pressure, divide the product of the final pressure and final volume by the initial volume.

Boyle’s Law Definition

Boyle’s law states that the pressure and volume of an ideal gas are directly proportional.

This formula is derived from the ideal gas law equation of pV = nRT. Since the change in temperatures and moles are the same in this reaction, that side of the equation can be canceled out

As mentioned previously, You can manipulate the equation above to calculate for any parameter, not just the final volume as this calculator displays. For instance, if you want to the calculator for the initial volume given the initial pressure, final volume, and final pressure, manipulate the equation as follows:

V₁ = p₂ * V₂ / p₁

You can do that in any combination, so as long as you have three of the known variables, you should be able to calculate the last variable easily.

How to Calculate Boyle’s Law

The following example will go over how to calculate an unknown pressure or volume of a gas using Boyle’s law.

  1. First, we must determine the missing variable we want to solve for. For this example, we are going to be searching for the initial volume.
  2. Next, we need to re-arrange the formula to solve for our miss variable. Luckily, we have already done this above under the formula section so, V₁ = p₂ * V₂ / p₁.
  3. The next step is determining or measure the known variables. this is typically done empirically, but could be done mathematically using other formulas like the ideal gas law formula. For this example, we will assume P2= 20 Pa, P1= 10 Pa, and V2 = 5 m^3.
  4. Finally, enter all of the information into the calculator or formula above and we find that V1 = 10 m^3.
  5. The last step is to analyze your results.


What is Boyle’s Law?

Boyles law states that the pressure and volume of an ideal gas are directly proportional.