Cell Density Calculator
Convert a hemocytometer count into cells per millilitre and the total number of cells in a culture, using the counted cells, squares counted and dilution factor.
How it works
cells/mL = (cells counted ÷ squares) × dilution factor × 10⁴ · total cells = density × volume
A standard hemocytometer chamber is 0.1 mm deep, and each large corner square is 1 mm × 1 mm, so one square holds exactly 1×10⁻⁴ mL of sample. The average number of cells per square, multiplied by the dilution factor and by the 10⁴ chamber constant, converts the count into cells per millilitre. Multiplying by the culture volume gives the total cell yield — the number you actually seed, freeze or treat.
Worked example
Counting 250 cells across 4 corner squares gives 62.5 cells per square. With a 2× (1:1 trypan blue) dilution: 62.5 × 2 × 10⁴ = 1.25×10⁶ cells/mL. In a 10 mL culture that is 1.25×10⁷ total cells.
Sources: Hemocytometer — Wikipedia
Frequently asked questions
Where does the 10⁴ factor come from?
Each 1 mm² counting square over the 0.1 mm chamber depth encloses 0.1 mm³ = 1×10⁻⁴ mL. Dividing the per-square count by that volume (i.e. multiplying by 10⁴) converts cells per square into cells per millilitre.
How many squares should I count?
Count the four (or five) large corner squares and average them for reliability; aim for 50–100 cells per square. Too few cells makes the count statistically noisy, too many makes it hard to count accurately.
What is the dilution factor for trypan blue?
Mixing cells 1:1 with trypan blue doubles the volume, so the dilution factor is 2. Adjust it for any other dilution you make before loading the chamber.
Related calculators
Educational estimate, not medical or laboratory advice — verify formulas, units and assumptions for your specific protocol.