Cell Dilution Calculator
The volume of cell suspension needed for a target seeding density — and the split ratio it corresponds to.
The volume needed is (target density × final volume) ÷ stock density.
How the cell dilution calculator works
The volume needed is (target density × final volume) ÷ stock density. Everything else is medium.
The split ratio is the other way of expressing the same thing, and the two are easy to confuse. A 1:10 split means one part cells to nine parts fresh medium; the resulting density is a tenth of the original, not a ninth.
Formula: V = (target × final volume) / stock density
Worked examples
| Inputs | Cell suspension needed | Note |
|---|---|---|
| 2M/mL stock to 200k/mL in 10 mL | 1 mL | 1 mL of cells into 9 mL of medium |
| A tighter split | 0.5 mL | 0.5 mL — a 1:20 split |
| Correcting for viability | 1 mL | more suspension needed |
FAQFrequently asked questions
How do I calculate a seeding volume?
Target density times final volume, divided by stock density. The rest of the final volume is fresh medium.
What does a 1:10 split mean?
One part cell suspension to nine parts medium, giving ten parts total at a tenth of the density.
Should I correct for viability?
Yes if you counted total rather than live cells. Dead cells do not contribute to growth, so seeding on a total count under-seeds the culture.
How do I count the cells?
A haemocytometer with trypan blue for viability, or an automated counter. Count enough squares — small counts carry large Poisson error.
Why does seeding density matter?
Too sparse and many lines grow poorly or differentiate; too dense and they reach confluence before the experiment. Both change the biology, not just the timing.
Where these figures come from
- NCBI Bookshelf — Molecular Biology of the Cell — growth kinetics and molecular conventions
- National Human Genome Research Institute — the US genomics research institute
Last checked: September 2026. Formulas are the standard textbook forms; assumptions are stated on each page because they are where these models break.