Cell Dilution Calculator
Use this cell dilution calculator to seed cells at a target density. Enter your counted stock density (cells/mL), the density you want, and the final volume — it returns the cell suspension to take and the fresh medium to add.
Enter stock density, the density you want, and the final volume to get the cell suspension and medium to add.
How to dilute a cell suspension
Cell density behaves like any concentration, so the dilution equation applies with the number of cells conserved:
C₁ is your counted stock density, C₂ is the density you want to seed, and V₂ is the final volume. Solve for the stock suspension volume:
The fresh medium to add is V₂ − V₁. Enter large densities in scientific notation such as 5e6 for 5 × 10⁶ cells/mL.
Worked example
Your stock is 5 × 10⁶ cells/mL and you want 1 × 10⁵ cells/mL in 10 mL: V₁ = (1e5 × 10) ÷ 5e6 = 0.2 mL of cell suspension, plus 9.8 mL of medium.
Typical seeding densities by application
"What density should I even seed at?" comes up as often as the math itself — these are common starting points, not hard rules:
| Application | Typical density |
|---|---|
| 96-well plate, adherent line | 1×10⁴ – 5×10⁴ cells/well |
| 6-well plate / T25 flask, adherent line | 1×10⁵ – 5×10⁵ cells/mL |
| Suspension line, routine maintenance | 2×10⁵ – 5×10⁵ cells/mL |
| Flow cytometry sample | ~1×10⁶ cells/mL |
| Transfection, day before (typical) | 2×10⁵ – 8×10⁵ cells/mL |
Related tools
For chemical stocks, use the home dilution calculator or the solution dilution calculator.
Frequently asked questions
›How do you dilute cells to a specific concentration?
Treat cell density like a concentration in C₁V₁ = C₂V₂. The stock suspension volume to take is V₁ = (desired density × final volume) ÷ stock density, and the medium to add is the final volume minus V₁.
›What is the cell dilution formula?
V_stock = (C₂ × V₂) ÷ C₁, where C₁ is your counted stock density (cells/mL), C₂ is the density you want, and V₂ is the final volume. Medium to add = V₂ − V_stock. You can type densities in scientific notation, e.g. 5e6.
›How do I calculate cell seeding density?
Decide the cells/mL you want in the plate and the total volume per well or flask, then use this calculator to find how much of your counted stock suspension to add and how much fresh medium to top up with.
›Does this work with cells/mL counted on a hemocytometer?
Yes. Enter your hemocytometer or automated-counter density as the stock density (C₁). Units cancel as long as C₁ and C₂ use the same units, so any consistent cells/mL value works.
›What if my counted density is lower than the density I want?
You can't concentrate a suspension by adding medium — only spinning it down and resuspending in less volume increases density. This calculator only handles the dilution direction (adding medium to lower density).
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