Haemocytometer calculator
Turn a chamber count into cells per millilitre, with the counting error stated.
One square holds 100 nL, so a count over one square multiplies by 10000 per mL.
Four corner squares is the usual protocol.
2 if you mixed one to one with trypan blue.
Unstained, across all the squares.
Stained blue. Leave blank to skip viability.
Live cells per mL
95% interval 715000 to 893000 — about ±11% on 320 cells counted.
Total cells per mL
800000
80 cells per square · 320 counted · ±10% would need about 385 cells, ±5% about 1537
About the Neubauer improvedThe default in most laboratories. Count the four 1 mm² corner squares; each holds 0.1 µL, which is where the familiar × 10⁴ comes from.
cells/mL = n ÷ (squares × area × depth) × D; 95% CI from ½·χ²(α/2, 2n) and ½·χ²(1−α/2, 2n+2)- Exact confidence limits for a Poisson count — Biometrika, 1936
- Score interval for a proportion, used for viability — Journal of the American Statistical Association, 1927
- Trypan blue exclusion test of cell viability — Current Protocols in Immunology, 1997
- Counting accuracy in a Neubauer chamber — Journal of Clinical Laboratory Analysis, 2019
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The interval covers counting error only — the randomness of how many cells happen to settle over the squares you read. It does not cover an unmixed suspension, cells lost to the coverslip edge, or clumps counted as one, all of which move the answer further than the statistics do. Mix well and load two chambers if the number matters.
About this tool
Convert a haemocytometer count into cells per millilitre for any chamber depth, with trypan blue viability, and see the confidence interval that the number of cells you counted actually supports. Counting is a Poisson process: 100 cells is roughly ±20%, and the tool says how many more to count for the precision you want.
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Science last reviewed .