Hemocytometer calculation

Once you have counted cells in each of the squares, you perform the hemocytometer calculations based on your total counts, dilution factor, initial volume and desired final density.

hemocytometer calculation formulas

hemocytometer calculator button


Now, here’s what you have to do to calculate your cell density manually or with Hemocytap, the hemocytometer app.

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:

hemocytometer equation cell density

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):

Hemocytometer volume equation

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.

Volume to add equation

If you have already suspended the cells in some new medium, you will need to substract this from the final volume to add:

hemocytometer equation resuspend

As Monsieur Malassez would say, “Voilà!”. For faster calculations, use our free hemocytometer calculator online:

hemocytometer calculator button

With the app:

If clicking on”subculture”, introduce the dilution, target density (recommended cell density) and initial volume. Get all the calculations above 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!

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I did my PhD in the Department of Chemical Engineering at Imperial College London. My research focused on mathematical modeling of the cell cycle in leukemia and involved experiments with cell lines. During that time, I had to count cells with a hemocytometer so often to track growth that I got tired and decided to build an app, HemocyTap, and share my knowledge on the topic here to help as many people as possible.

Latest posts by Maria Fuentes, PhD (see all)

11 comments on “Hemocytometer calculation

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  3. […] you are not messing it up with the numbers. For a printable protocol, click here. Finally, go to Hemocytometer calculation for a detailed explanation on what to do with your […]

  4. […] the calculations as in hemocytometer calculation, except that you have to multiply by 10000*25 = 250000 (because there are 25 small squares in a 1mm […]

  5. Ho do you find what dilution is the most accurate to calculate cell concentrations for your original sample, from the density??

    • Thanks for your question. Please see my answer here

  6. Hi Maria, I have a question why does the Original cell concentration (ml^-1) increase as the dilution increases ??

    • Hi Samuel,
      The more you dilute, the less cells from the original sample remain in the diluted volume. To account for this, you multiply by the number of times you have diluted. For example, you have 100,000 cells/mL in the original sample. You dilute once (let’s say 50uL in 50uL of trypan blue; this is a 1:1 dilution or dilution factor equal to 2), the concentration should be half right? So you dilute once, the concentration in your diluted solution is 50,000 cells/mL. Now let’s say you dilute once your diluted solution: you had 50,000 cells/mL, you take 50uL from there and 50uL trypan blue or water (this is a 1:1 dilution or dilution factor equal to 2 from the diluted solution, or 1:3 dilution / dilution factor 4 from the original sample), you get 25,000 cells/mL. As you can see, in the first dilution you had a dilution factor of 2 and concentration of 50,000 cells/mL while in the second you had a dilution factor of 4 (from the original) and a concentration of 25,000 cells/mL. To calculate the original concentration backwards, you would multiply the dilution factor by the concentration. For the first dilution, this is 2 x 50,000 cells/mL = 100,000 cells/mL. For the second dilution, this is 4 x 25,000 cells/mL = 100,000 cells/mL.

      Therefore, the original cell concentration is always the same for the same sample. Depending on how many times you dilute, the dilution factor will change.

      Was that clear? Cheers


  7. Yes its very clear thank you 😀

  8. Hi maria, I have a question Why some equation should to multiply by 10,000 cell/ml and multiply dilution factor?

    for example this equation
    [ Total cell/ml= Total cells counted x (dilution factor/# of squares) x 10,000 cell/ml ]

    why they multiply by 10,000 cell/ml?

    • Hi there,

      You multiply by the dilution factor if you want to find out the original cell concentration, i.e., previously to any dilutions you have performed specifically for counting cells. The 10,000 factor is not in cell/mL but in mL^-1 (or 1/mL). It represents the inverse of the volume of one of the corner squares, which is calculated as the area: 1 mm x 1 mm = 1 mm^2 times the height of the space between the hemocytometer and the coverslip (0.1mm), or 1 mm^2 x 0.1 mm = 0.1 mm^3 = 0.0001 mL. When you do the inverse, 1/0.0001 mL^-1 = 10,000 mL^-1 which is the factor you are using. You can find more details about these calculations in my other post on hemocytometer sizes.

      Hope that helped!


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