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Hemocytometer Cell Count Calculator

Converts a hemocytometer count into cell concentration with cells/mL = (cells counted ÷ large squares counted) × dilution factor × 10⁴, and optionally the total cells in a sample, trypan-blue viability and the volume that contains a target number of cells.

When to use

You counted cells in the large 1 mm² squares of a Neubauer hemocytometer and need the concentration, the number of cells in your flask or the volume to seed a given number of cells.

Do not use when: You counted in the small central squares or used a different chamber depth (adjust the volume per square), used an automated counter, or need cell growth rates (use cell-doubling-time).

Formula

cells/mL = (cells_counted / squares_counted) × dilution_factor × 10⁴; total = cells/mL × sample_volume_ml; viability % = 100 × live / (live + dead); volume_for_target = target_cells / cells/mL

Standard Neubauer geometry: each large square is 1 mm × 1 mm × 0.1 mm = 0.1 µL, so cells per square × 10⁴ = cells per mL. Counting error follows Poisson statistics (≈ 10 % for 100 cells, 7 % for 200), which is why at least 100 cells should be counted.

Inputs

ParameterTypeUnitRequiredDescription
cells_countedintegeryesNumber of (live, unstained) cells counted in all the squares together. Range: ≥ 0, ≤ 10000000
squares_countedintegerdefault 4Number of large 1 mm × 1 mm squares counted (each holds 0.1 µL at the standard 0.1 mm depth); typically the 4 corner squares. Range: ≥ 1, ≤ 18
dilution_factornumberdefault 1Dilution of the sample before loading (2 for a 1:1 mix with trypan blue, 10 for 1:9). Range: ≥ 1, ≤ 1000000
sample_volume_mlnumbermLnoVolume of the original cell suspension; gives the total cell number. Range: > 0, ≤ 1000000
dead_cells_countedintegernoStained (dead) cells counted in the same squares; gives the viability. Range: ≥ 0, ≤ 10000000
target_cellsnumbernoNumber of cells you want to take; gives the suspension volume needed. Range: > 0, ≤ 1000000000000000

Outputs

OutputTypeUnitDescription
cells_per_mlnumbercells/mL(cells_counted / squares_counted) × dilution_factor × 10⁴.
cells_per_ml_textstringThe concentration in scientific notation.
cells_per_squarenumbercells_counted / squares_counted.
poisson_counting_error_percentnumber%Relative standard error of the count, 100 / √cells_counted.
total_cellsnumbercells_per_ml × sample_volume_ml (when the volume is given).
viability_percentnumber%100 × live / (live + dead) (when dead_cells_counted is given).
total_cells_per_mlnumbercells/mLConcentration including dead cells (when dead_cells_counted is given).
volume_for_target_mlnumbermLtarget_cells / cells_per_ml (when target_cells is given).

Example

200 cells in 4 squares, 1:1 trypan blue, 10 mL flask: {"cells_counted":200,"squares_counted":4,"dilution_factor":2,"sample_volume_ml":10,"dead_cells_counted":20,"target_cells":1000000} → {"cells_per_ml":1000000,"cells_per_ml_text":"1.00 × 10^6 cells/mL","cells_per_square":50,"total_cells":10000000,"viability_percent":90.91,"volume_for_target_ml":1,"poisson_counting_error_percent":7.07}

120 cells in 4 squares, undiluted: {"cells_counted":120,"squares_counted":4,"dilution_factor":1} → {"cells_per_ml":300000,"cells_per_ml_text":"3.00 × 10^5 cells/mL","cells_per_square":30}

GET https://tttkmbb.com/api/v1/calculate/hemocytometer-count?cells_counted=200&squares_counted=4&dilution_factor=2&sample_volume_ml=10&dead_cells_counted=20&target_cells=1000000

Machine access

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FAQ

Do I enter live cells only?

Enter the unstained (live) cells as cells_counted and the blue (dead) cells as dead_cells_counted; the main concentration is then viable cells per mL and viability is live / (live + dead).

Which dilution factor for trypan blue?

Mixing equal volumes of cells and 0.4 % trypan blue is a 1:1 dilution, so the factor is 2; 10 µL cells + 90 µL stain is a factor of 10.

How many cells should I count?

At least 100 in total (ideally 100–200 per large square set); dilute if squares are overcrowded (> 200 per square) and count more squares if there are fewer than about 20 per square.

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