Cell Membrane & Osmosis Simulator
Place a cell in a hypotonic, isotonic or hypertonic solution and watch water cross the membrane while a live graph tracks the cell's volume.
Place the cell in a hypotonic, isotonic or hypertonic solution and watch water cross the membrane. The cell swells, shrinks or stays the same depending on the concentration gradient.
About the Cell Membrane & Osmosis Simulator
Free cell membrane & osmosis simulator. Place a cell in a hypotonic, isotonic or hypertonic solution and watch water cross the membrane while a live graph tracks the cell's volume. Drag, change the sliders and see the result live. No sign-up, works on phone and computer. Built for biology, the cell membrane & osmosis simulator runs instantly in your browser: change a setting or drag an object and the result updates at once, so you learn by trying things out rather than only reading about them.
Place a cell in a hypotonic, isotonic or hypertonic solution and watch water cross the membrane while a live graph tracks the cell's volume. Use it to explore biology ideas at your own pace, then check what you found against the key ideas further down this page.
How to use the Cell Membrane & Osmosis Simulator
- Use the controls to change External solute concentration, Membrane permeability, Temperature, Preset. The simulation reacts instantly.
- Pick an option such as Hypotonic, Isotonic, Hypertonic to switch modes or load an example.
- Press "Reset to defaults", "Check cell volume", "📄 Lab Report" to start, reset or change what is happening.
- Where you see a glowing handle, object, weight or atom, drag it with your mouse or finger. Everything responds in real time.
- Watch the readouts and graphs update as you experiment, and compare what you see with the key ideas below.
Things to try
- Load the Hypotonic preset and watch the cell swell.
- Load the Hypertonic preset and watch it shrink.
- Raise permeability and see how much faster the same outcome happens.
- Try the challenge: shrink the cell below 70% of its starting volume without lysing it.
Key ideas you can learn
- Water moves from a region of lower solute concentration to higher solute concentration (osmosis).
- In a hypotonic solution a cell swells and may lyse (burst); in a hypertonic solution it shrinks (crenates).
- In an isotonic solution there is no net water movement and the cell stays the same size.
- Higher membrane permeability and higher temperature both speed up how fast equilibrium is reached.
Where this is used in the real world
Doctors choose IV fluids that are isotonic to blood for exactly this reason, and this is also why plant cells rely on a rigid cell wall to resist bursting in hypotonic conditions.
Who is this simulation for?
Biology students and teachers who want to explore living systems, populations and genetics interactively and safely.
For teachers: project it on the board, let students predict what will happen, then run it together. For students: change one thing at a time and write down what changes.
Frequently asked questions
Why do red blood cells burst in pure water?
Pure water has almost no solute, so water rushes into the cell by osmosis until the membrane can no longer hold it.
What does isotonic mean?
The solute concentration outside the cell equals the concentration inside, so there is no net water movement.
Is the Cell Membrane & Osmosis Simulator free to use?
Yes. It is completely free, with no signup, no download and no ads inside the simulation. It runs in your web browser.
Does the Cell Membrane & Osmosis Simulator work on a phone or tablet?
Yes. It uses touch as well as the mouse, so you can drag objects with your finger. A larger screen makes the controls easier to see.