How Small Are We Talking?

A typical bacterium is around two micrometers (2 μm) — or 0.002 millimeters (0.002 mm) — long.

That’s between 10 and 100 times smaller than the thickness of a human hair!

Yep, that’s pretty tiny. Far too small to see with your naked eyes, so scientists need to use microscopes to study bacteria.

Find out here how a microscope actually works!

And if you want to play around with a microscope yourself and look at different types of samples, then take a look through our virtual microscope!

Discover what bacteria, blood cells and spider legs look like from VERY close up.

Please click on the screenshot to open the simulation on an external website.

Can you guess which organisms are the smallest and biggest?

Rank them in order of average size!

If you have a go, take a photo and send it to us!

Bacteria are among the most common and important living things on the planet. Click and say hi!