Hemocytometer calculations using calculator

How to manually calculate the viable cell concentration

Viable Cell Concentration= Average number of cells per square * Dilution factor * 10⁴
If you are wondering where did 10⁴ came from, here is the explanation below.
Each square has a volume of 0.1μl = 0.0001 mL (you are calculating cell/mL). Instead of dividing by 10⁻⁴, you multiply by 10⁴ (it’s the same).

Example question

You are a researcher tasked with the setting up a series of experiments and analysing the resultant data from a study of the effects of the organophosphate chlorpyrifos on the viability and differentiation of cultured mouse N2a neuroblastoma cell line, as indicated below. You are required to handle, analyse, present and interpret the data provided, providing evidence of how you have arrived at your conclusions Cells were grown as a mitotic monolayer to approximately 80% confluence then detached for counting. After centrifugation of the resultant cell suspension, cell pellets werere suspended in 1 mL growth medium. A volume of 10 µL of this cell suspension was mixed with 90 µL growth medium containing 0.2 % v/v Trypan Blue, after which the cells analysed in a haemocytometer, giving the data shown in Table 1.

Square number*	Total cell count	Blue (dead) cell count
1	99	3
2	115	8
3	87	6
4	105	5
5	125	9

*Each haemocytometer square has a volume of 10^-4mL. Using the data in Table 1, calculate the following parameters.

(i) Calculate total cell count/ml
(ii) Viable cell count/ml
 (iii) % VIABILITY

Answer (i) Total cell count/mL means we have to calculate total number of live and dead cells.
Total cell count/mL = Average of total cells per square x dilution factor x 10⁴
Average of total cells per square= 99+ 115 + 87 + 105 + 125/5= 106.2
Dilution factor= 100/10= 10
Total cell count/mL = 106.2 x 10 x 10⁴  = 1.062 x 10⁷ =10,620,000 cells/mL = 10.62 million cells/mL

Answer (ii) Viable cell count/mL = Average viable count per square x dilution factor x 10⁴
For each square, calculate the number of viable cells = Total count – blue cell count
Average viable count per square= 96+107+81+100+116/5 = 100

Viable cell count/ml = Average viable count per square x dilution factor x 10⁴
Viable cell count/ml = 100 x 10 x 10⁴ = 1 x 107 viable cells/mL = 10 million viable cells/mL

Answer (iii) % Viability= Total number of viable cells per ml/Total cell count per ml
% Viability= 10 million/10.62million x 100 = 94.2%

OR
% Viability= Average viable count per square/Average of total cells per square
% Viability= 100/106.2 x 100 = 94.2%