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Partial Pressure Calculator

Partial Pressure Calculator

Choose Formula:

To Calculate:

Total Pressure:


Mole Fraction:

Partial Pressure:


To Calculate:

Amount of Mole:






Partial Pressure:


To Calculate:


Henry's law constant:




Partial Pressure:


To Calculate:


Henry's law constant:


Mole Fraction:

Partial Pressure:


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An online partial pressure calculator is properly designed to calculate partial pressure, volume, temperature, and amount of moles of each individual gas enclosed in a container. Before you move further, you need to understand important gas laws which are explained below.

Keep reading!

What Is A Partial Pressure?

In the context of chemistry:

“In a mixture of gases, the pressure exerted by each individual gas separately is known as the partial pressure.”

For example:

Partial pressures of some important gases are as follows:


Partial Pressure





Carbon Dioxide





Partial Pressure Formula:

Uptill now many theories have been published for calculating partial pressure in a gas mixture. Some of the important gas laws that are widely used to calculate the partial pressure are as follows:

Dalton’s Law Of Partial Pressure:

This law states that:

“In a mixture of gases that is enclosed in a container, the total pressure exerted on the walls of the container is actually equal to the sum of the individual partial pressures exerted by each gas separately”

Dalton’s Law Of Partial Pressure Formula:

$$ \text{Total Pressure} = P_{1}+ P_{2}+, …, +P_{N} $$

The equation for partial pressure is as follows:

$$ \text{Partial Pressure} = \text{Total Pressure} * \text{Mole Fraction} $$

Mole Fraction:

“It is defined as the ratio of the number of moles of selected gas to the number of moles of the entire gas”.


$$ \text{Mole Fraction} = \frac{\text{ No. Of Moles Of Selected Gas}}{\text{No. Of Moles Of Entire Gas Mixture}} $$

Also, you can use a free online mole fraction calculator to find the exact results for this quantity.

Ideal Gas Law:

This gas law is a generic law which supports the relationship among different properties of an ideal gas. The relationship equation is given below:

$$ P*V = n*R*T $$


P = Pressure of the gas
V = Volume of the gas
n = No.of moles of the gas
T = Temperature of gas
R = Universal gas constant

$$ R = 8.3145 \frac{J}{mol * K} $$

$$ R = 0.08206atm.L.mol^-1.K^-1 $$

Now if we divide the product of number of moles of a specific gas, temperature, and gas constant by volume of the entire mixture, we can get the partial pressure formula to determine this specific term accurately:

$$ \text{P_{i}} = \frac{n_{i}*R*T}{V} $$


P_i = Partial pressure of the individual gas
n_i = No. of moles of the individual gas
T = Temperature of the whole gas mixture
V = Volume of the whole gas mixture

Henry’s Law:

This is indeed the most important partial pressure gas law considered so far. This law states that:

“ The amount of the gas dissolved in a certain liquid and the partial pressure of the gas accumulated above the surface of that liquid are proportional to each other”

Partial Pressure Equation:

Here we have two different methods that can be used to find the partial pressures of the individual gases accurately. These both methods are as follows:

Method # 01:

When you are given the concentration of the solution:

$$ Pressure = K_{H1} * Concentration $$


K_H1 = Henry’s law constant that is measured in the units of [litre * atm / mol].

Method # 02:

When the solute’s mole fraction is given:

$$ Pressure = K_{H2} * Mole Fraction $$


K_H2 = Henry’s law constant in atm

Here the free Henry’s law calculator uses both of these methods to determine various terms absolutely and in a glimpse of an eye.

How To Calculate Partial Pressure?

You can use our partial pressure calculator to determine analogous terms to gases absolutely. But it is also mandatory to have a hands on grip on manual calculations. This is why we will be solving a couple of examples to make your concept much clearer:

Example # 01:

The total pressure exerted nb7y a mixture of hydrogen and oxygen on the walls of the container is 2.3 atm. If the partial pressure exerted by hydrogen alone is approximately 2atm,what will be the mole fraction of the oxygen in the whole mixture?


We know that:

$$ \text{Total Pressure} = P_{H_{2}}+ P_{O_{2}} $$
$$ 2.3 = 2 + P_{O_{2}} $$
$$ P_{O_{2}} = 2.3 – 2 $$
$$ P_{O_{2}} = 0.3 $$

Now we have:

$$ X_{oxygen} = \frac{P_{oxygen}}{P_{total}} $$

$$ X_{oxygen} = \frac{0.3}{2.3} $$

$$ X_{oxygen} = 0.130 $$

Here our free online partial pressure calculator finds the same results but in a fraction of time to save your precious time.

Example # 02:

At a specific temperature of 200K, 20litres of gas A and 10 litres of gas B are transformed in a 10L container at pressures 1atm, and 3atm, respectively. How to find total pressure?


We now the ideal gas equation:

$$ P*V = n*R*T $$

First of all, we need to find the number of moles of both gases:

$$ \text{No. of Moles of Gas A} = \frac{20L * 1atm}{ 0.08206atm.L.mol^-1.K^-1 * 200K} $$

$$ \text{No. of Moles of Gas A} = 1.21 mol $$

$$ \text{No. of Moles of Gas B} = \frac{10L * 3atm}{ 0.08206atm.L.mol^-1.K^-1 * 200K} $$

$$ \text{No. of Moles of Gas B} = 1.82 $$

$$ \text{Total Number Of Moles} = 1.21 + 1.82 $$

$$ \text{Total Number Of Moles} = 3.03mol $$

Calculating total pressure inside the 10L as follows:

$$ P_{total} = \frac{n*R*T}{V} $$

$$ P_{total} = \frac{3.03mol * 0.08206atm.L.mol^-1.K^-1 * 200K}{10L} $$

Example # 03:

Suppose there are four gases A, B, C, and D enclosed in a container. Each gas exerts pressure on the walls of the container which are 3atm, 2atm, 5atm, and 4atm, respectively. How to calculate total pressure from partial pressure?


Converting partial pressure to total pressure:

$$ \text{Total Pressure} = P_{A} + P_{B} + P_{C} + P_{D} $$

$$ \text{Total Pressure} = 3atm + 2atm + 5atm + 4atm $$

$$ \text{Total Pressure} = 14atm $$

Which is our required answer.

Example # 04:

We are given the value of Henry’s constant as \(2.3 * 10^3 L . atm. mol^-1\) at a temperature of 198K. How to find partial pressure for which the solubility of the gas becomes \(2.4 * 10^-4\)M?


We are given:

$$ k_{H} = 2.3 * 10^3 L . atm. mol^-1 $$
$$ C = 2.4 * 10^-4 M $$
We know that:

$$ Pressure = K_{H1} * Concentration $$

$$ Pressure = 2.3 * 10^3 L . atm. mol^-1 * 2.4 * 10^-4 M $$

$$ Pressure = 0.384atm $$

How Partial Pressure Calculator Works?

Well, our free calculator finds the accurate outputs regarding various important terms for gases. But it does not mean that you can not use it. We have designed it in such a way that you will never feel difficulty in using it. For instance, let us guide you how to use it?


First, you need to select one of the following methods:

  • Dalton’s law of partial pressure
  • Ideal gas law
  • Henry’s law (Method 1)
  • Henry’s method (Method 2)

If you select Dalton’s law method, further select either of the given options in “To Calculate” drop down menu:

  • Partial pressure
  • Mole fraction
  • Enter Required parameter values
  • Hit the calculate button

If you select Ideal Gas Law, further make a choice about what you need to determine from the following in “To Calculate” drop down list:

  • Partial pressure
  • Volume
  • Temperature
  • Amount of moles
  • Click on calculate

If you choose Henry’s method 1, make a further selection about what you wish to find from the following:

  • Partial pressure
  • Concentration
  • Tap the calculate button

In case you do choose Henry’s method 2, choose what next you wish to work for which can be either of the following:

  • Partial pressure
  • Mole fraction
  • Hit the calculate button


The free henry’s law calculator determines:

  • Partial pressure
  • Mole fraction
  • Volume
  • Concentration
  • Temperature
  • Amount of moles


What do you mean by an ideal gas?

A hypothetical gas that consists of many point particles having no forces among them is called an ideal gas.

What does Boyle’s law demonstrate?

Boyle’s law determines the relationship between a gas volume and pressure. It states that:

“The pressure that is exerted by a gas is always inversely proportional to the volume of the gas, keeping the temperature constant”.

Why ice occupies more space than water?

Yes, it is true that ice always occupies more space than water. This is because when water molecules freezes, they occupy 9% more space than before.


Without partial pressure, we are actually unable to make an estimation about gases. Chemists widely use free online partial pressure calculator while performing various chemical reactions. This is because this calculator gives most accurate results that are very crucial to avoid any disturbance in the reaction.


From the source of Wikipedia: Kinetic theory of gases, Equilibrium properties, Transport properties.

From the source of Khan Academy: real gases, Deviations from ideal behavior, The van der Waals equation, Non-ideal behavior of gases.

From the source of Lumen Learning: Charles’ and Gay-Lussac’s Law, Extrapolation to Zero Volume.