Cell Counter — Count cells in a microscope image from a photo

Counting cells in one microscope image as a quick second read

Researchers and lab teams use this cell counter for a quick draft count alongside their established method: repeat reads of the same field, comparing two fields captured at the same magnification, or a training record where the marked image shows what was counted. It is not a hemocytometer replacement or a regulated method, and every count is a draft you review.

Work from a sharp, evenly lit image. A phone held to the eyepiece produces a bright circle with dark corners, so crop to the circle with the image cropper to keep the dark edge out of the count. Hemocytometer grid lines cross the field and can interfere, so choose a field where cells are not sitting on the lines, or count inside one square. Mark two or three typical cells as examples in Similar items. If the sample is stained for viability, marking one stained and one unstained cell gives a Found per example split that you still check by eye.

Clumped cells, debris and cells out of focus in another plane cause most errors, so review each marker and correct the tally row. Label rows by sample and field; any concentration or viability figure is your own calculation from the reviewed counts. For colonies on agar rather than cells under a microscope, see the colony counter for plates.

Microscope image checks

• Sharp focus on one plane of cells
• Image cropped to the bright field of view
• A field away from grid lines where possible
• The same magnification for fields you plan to compare