Osmotic Pressure Calculator
Osmotic pressure calculator using the van 't Hoff equation Π = iCRT, or the concentration from a pressure.
Π = i · C · R · T
How to use this calculator
- Choose the quantity you want under “Solve for”.
- Type the known values and pick their units: any combination works.
- The result updates as you type. Open “Show the steps” to see the substitution.
i is the number of particles per formula unit (1 for glucose, about 2 for NaCl).
Osmotic pressure drives water across membranes: the basis of reverse osmosis and IV solution design.
Formula
Π = i · C · R · T
| Symbol | Quantity | Units |
|---|---|---|
| i | van 't Hoff factor | — |
| C | Molar concentration | mol/L, mmol/L, µmol/L, nmol/L, mol/m³ |
| T | Temperature | K, °C, °F, °R |
| Π | Osmotic pressure | Pa, kPa, MPa, hPa, bar, mbar, atm, Torr, mmHg, psi, inHg |
Constants used: R = 8.314 J/(mol·K)
Worked example
Given: i = 1 · C = 0.1 mol/L · T = 25 °C
Π = i C R T
Result: Π = 2.44654 atm
Frequently asked questions
0.1 M glucose at 25 °C?
About 2.45 atm.