Osmotic Pressure Calculator
Calculate the osmotic pressure of a solution from its molar concentration, van’t Hoff factor, and temperature using π = iMRT.
What is osmotic pressure?
Osmotic pressure is the pressure needed to stop the net flow of solvent across a semipermeable membrane by osmosis. It depends on how many dissolved particles are in the solution, not what those particles are.
How this calculator works
This calculator uses the van’t Hoff equation for osmotic pressure: π = iMRT, where π is osmotic pressure, i is the van’t Hoff factor (the number of particles a solute produces in solution), M is molarity, R is the ideal gas constant (0.08206 L·atm/(mol·K)), and T is absolute temperature in kelvin.
The temperature you enter in Celsius is automatically converted to kelvin before the calculation. For a non-electrolyte like glucose, i is 1; for an electrolyte like NaCl that fully dissociates into two ions, i is close to 2.
This tool is for general chemistry education purposes.