Enter the pressure (Pa), the molecular weight (kg/mol), and the temperature (K) into the Density From Molecular Weight Calculator. The calculator will evaluate and display the Density From Molecular Weight. 

Density From Molecular Weight Formula

The following formula is used to calculate the Density From Molecular Weight. 

D = P * MW / (R*T)

  • Where D is the Density From Molecular Weight (kg/m^3)
  • P is the pressure (Pa) 
  • MW is the molecular weight (kg/mol) 
  • T is the temperature (K) 
  • R is the Universal Gas Constant (8.314)

How to Calculate Density From Molecular Weight?

The following example problems outline how to calculate Density From Molecular Weight.

Example Problem #1

  1. First, determine the pressure (Pa).
    1. The pressure (Pa) is given as 3000.
  2. Next, determine the molecular weight (kg/mol). 
    1. The molecular weight (kg/mol) is calculated as: .44.
  3. Next, determine the temperature (K). 
    1. The temperature (K) is found to be: 250.
  4. Finally, calculate the Density From Molecular Weight using the formula above: 

D = P * MW / (R*T)

Inserting the values from above yields: 

D = 3000 * .44 / (8.314*250) = .635 (kg/m^3)


Example Problem #2

The variables needed for this problem are provided below:

pressure (Pa) = 240

molecular weight (kg/mol) = 205

temperature (K) = 100

This example problem is a test of your knowledge on the subject. Use the calculator above to check your answer. 

D = P * MW / (R*T) = (kg/m^3)