Yeast Cell Count Calculator
Cells per mL and total cell count from a haemocytometer tally, plus live/dead viability.
Viability (optional)
How it works
A haemocytometer holds a precise volume over each ruled square. For a Neubauer chamber a large 1 mm × 1 mm square with a 0.1 mm depth holds 0.1 mm³, i.e. 0.0001 mL. Averaging your count over the squares you counted and dividing by that volume (which multiplies by 10,000), then scaling by the dilution factor, gives cells per mL. Multiplying by your slurry volume gives the total cell count you can compare against a pitch-rate target.
cells/mL = (cells counted / squares counted) × dilution × 10,000
total cells = cells/mL × slurry mL
viability % = live / (live + dead) × 100
This is the count-to-concentration calculation. Automated counting from a microscope photograph is a separate tool and is not done here - you supply the tally.
Sources: haemocytometer chamber geometry and the ×10⁴ factor per standard Neubauer / Bright-Line protocols and White & Zainasheff, Yeast (2010).
Frequently asked questions
- How do I count yeast on a haemocytometer?
- Dilute your sample (often 1:100 or more so cells are countable), load the chamber, and tally the cells in a known number of large 1 mm × 1 mm squares under the microscope. Enter the total counted, how many squares you counted, and the dilution factor - the tool returns cells per mL.
- Where does the ×10,000 come from?
- A large Neubauer square is 1 mm × 1 mm with a 0.1 mm coverslip gap, so the volume above it is 0.1 mm³ = 0.0001 mL. Dividing the average count per square by that volume multiplies by 10,000 - that is the standard haemocytometer factor.
- How do I get viability?
- Stain the sample (methylene blue or trypan blue) so dead cells take up colour, then tally live and dead separately. Enter both and the tool gives the live percentage. Multiply your total cells by viability to get the viable count you actually pitch.