How Do I Estimate Cell Size Under a Microscope?
Because the individual cells of any organism are too small to be seen with the naked eye, we must use microscopes to magnify them. We can view a cell at a magnification of up to 1000x under a light microscope, but we can’t gauge its actual size just by looking at it. However, we can accurately estimate a cell’s size by doing a little bit of math. Look at the revolving nosepiece, or turret, of your microscope and identify the objective lenses. Typically, you will find a 4X, 10X, 40X and possibly a 100X objective lens. Place the 10X objective lens in position, leaving off the microscope slide for the moment. Turn on the microscope’s light source, and adjust it for eye comfort while looking through the eyepiece lens. You should see a white circle of light. This is the “field of view” of your microscope. Place your metric ruler on the microscope stage, and move it into a position where you can see it clearly. Align one side of the ruler with the left edge of the field of view, and measure
