Osmotic Pressure Calculator
Calculate osmotic pressure from solute concentration and temperature.
About Osmotic Pressure Calculator
Osmotic pressure is surprisingly large: physiological saline at 0.15 M generates about 7.6 atm, equivalent to a 78-metre column of water. That is why cells rupture in pure water. Reverse osmosis must apply pressure exceeding the osmotic pressure of the feed, which is why desalinating seawater needs 50 to 80 bar.
Formula
Osmotic Pressure
Π = i M R T, the van’t Hoff equation for osmotic pressure
- Π
- Osmotic pressure
- osmolarity
- Total particle concentration, i × M
Worked example
With the default values below, Osmotic Pressure Calculator returns Osmotic Pressure of 7.6350. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Molar concentrationminimum 0 mol/L
- 0.15 mol/L
- Van’t Hoff factoraccepts 1–10
- 2
- Temperatureaccepts -50–200 C
- 37 C
Results
- Osmotic Pressure
- 7.6350 atm
- Osmotic Pressure
- 7.7362 bar
- Osmolarity
- 0.3000 osmol/L
- Osmotic Pressure
- 773,615.7 Pa
- Equivalent Height of Water
- 78.86 m
Step by step
- 1Values used
- 2Osmotic Pressure
- 3Osmotic Pressure= 7.6350 atm
- 4Osmotic Pressure= 7.7362 bar
- 5Osmolarity= 0.3000 osmol/L
- 6Osmotic Pressure= 773,615.7 Pa
- 7Equivalent Height of Water= 78.86 m
Assumptions and limits
- The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Osmotic Pressure calculated?
Π = i M R T, the van’t Hoff equation for osmotic pressure Osmotic pressure is surprisingly large: physiological saline at 0.15 M generates about 7.6 atm, equivalent to a 78-metre column of water. That is why cells rupture in pure water.
Why does Osmotic Pressure matter?
Reverse osmosis must apply pressure exceeding the osmotic pressure of the feed, which is why desalinating seawater needs 50 to 80 bar.
What values do I need to enter?
This calculator takes 3 inputs: Molar concentration, Van’t Hoff factor, Temperature. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.