Hemocytometer Calculator
Turn the cells you counted on a hemocytometer (haemocytometer) into cells per mL, viability, total cells, and the volume of suspension to seed.
Calculator
Count your cells
2 after mixing 1:1 with trypan blue, 1 if undiluted.
All squares together. Without a stain, count every cell here.
The blue ones, for viability.
For the total number of cells.
For the volume of suspension to use.
Enter the squares counted, live cells counted and dilution factor to see the cells per mL.
Worked example
Four large squares, 1:1 in trypan blue
- 01live cells: 52 + 47 + 55 + 46 = 200; dead: 10
- 02(200 ÷ 4) × 2 × 10⁴ = 10⁶ live cells/mL
- 03viability = 200 ÷ 210 = 95.2%
10⁶ live cells/mL, at 95.2% viability.
How it works
The reasoning behind it
A hemocytometer is a slide with a counting grid and a chamber of known depth, 0.1 mm. The grid's large squares are 1 mm across, so each holds 0.1 µL of your sample.
Counting the cells over several squares and averaging gives the cells in 0.1 µL. Multiplying by 10⁴ turns that into cells per mL, and multiplying by the dilution factor undoes any dilution made before loading.
Trypan blue gets into cells whose membranes are damaged, so blue cells are counted as dead. Viability is the live cells as a percentage of all the cells counted.
Questions
Frequently asked
Why multiply by 10,000 in a hemocytometer count?
One large square holds 0.1 µL, which is 10⁻⁴ mL. The cells over one square are the cells in 10⁻⁴ mL, so multiplying by 10⁴ gives cells per mL.
How do I calculate cell viability?
Divide the live (unstained) cells by all the cells counted, live and dead, and multiply by 100. 200 live and 10 dead cells is 200 ÷ 210 × 100 = 95.2%.
How much cell suspension do I need to seed a flask?
Divide the number of cells you want by the live cells per mL. To seed 5 × 10⁵ cells from a suspension of 10⁶ cells/mL, use 0.5 mL.
Which squares should I count?
For cultured cells, count the four large corner squares, and the centre one as well if you like. For small, dense cells such as red blood cells, count the small squares in the centre grid and choose small squares in the calculator.
More Calculators
Each one shows its formula and a worked example, so you can check the answer and learn the method.
Serial Dilution Calculator
The volume to transfer, the diluent for each tube and the concentration in every tube of a dilution series.
Open calculatorDilution Calculator
How much stock to dilute, or the final concentration or volume, with C₁V₁ = C₂V₂.
Open calculatorNormal Lab Values
Typical adult ranges for blood, urine and spinal fluid tests, in conventional and SI units, with a source for every value.
Open the table