Fine. You have your counts. Now, here’s what you have to do with and without HemocyTap, the hemocytometer app.
With the app:
If clicking on”subculture”, introduce the dilution, target density (recommended cell density) and initial volume. Get all the calculation below done for you and read the volume you need to add. Check here for a detailed video on how to do it.
If clicking on “cell density”, introduce the dilution and the initial volume (only if you want to know the total cells). You will get the cell density (and the cell number if you gave the initial volume) as per the calculations below.
Save for your records. Ta-da!
Without the app:
Take the average of cells per square (sum of all cells in each small square you have counted, divided by the total number of squares you have counted), multiply it by the dilution factor (if you haven’t diluted your sample, multiply by 1) and divide by the volume (in mL) of a small square, following the equation:
The volume of a small square is specific to the hemocytometer. It is calculated by multiplying the width by the height (which are the same – usually 1mm each) by the depth (usually 0.1mm) of a small square. In the most common case, this would be (check here to find out the volume of other squares):
With the measured cell density obtained, you are going to calculate how much more medium you need in order to reach the manufacturer’s recommended cell density.
If you have already suspended the cells in some new medium, you will need to substract this from the final volume to add:
As Monsieur Malassez would say, “Voilà!”.