Cell seeding density calculator
The number of cells to seed is the target density times the vessel's growth area: cells = cells/cm² × cm². A 6-well plate well is 9.6 cm², so seeding at 2 × 10⁴ cells/cm² takes 1.9 × 10⁵ cells per well; dividing by your stock concentration gives the volume to pipette.
Result
cells = density × growth area. Areas follow Corning's growth-area chart (e.g. 6-well 9.6 cm², T-75 75 cm²) — check your vendor's insert, areas differ slightly between brands.
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Formula
cells = density (cells/cm²) × growth area (cm²) · volume = cells / stock (cells/ml)
Worked example
Given: Six wells of a 6-well plate at 2 × 10⁴ cells/cm², stock at 1 × 10⁶ cells/ml
- 1.Per well: 2 × 10⁴ × 9.6 = 1.92 × 10⁵ cells.
- 2.Six wells: 1.15 × 10⁶ cells total.
- 3.Stock volume: 1.15 × 10⁶ / 1 × 10⁶ = 1.15 ml, split across the wells in complete medium.
1.92 × 10⁵ cells per well; 1.15 ml of stock for the plate
How the calculation flows
Units & constants
| 96-well | 0.32 cm² per well |
|---|---|
| 24-well | 1.9 cm² per well |
| 6-well | 9.6 cm² per well |
| 100 mm dish | 56.7 cm² |
| T-25 / T-75 / T-175 | 25 / 75 / 175 cm² |
| Source | Corning growth-area chart; areas vary slightly by vendor |
| Price | Free |
What seeding density should you use?
It depends on the line and the experiment's timeline. Adherent workhorses (HEK293, HeLa, CHO) are commonly seeded at 1–5 × 10⁴ cells/cm² to reach 70–90% confluence in 2–3 days. Seed low for long experiments and clonal growth; seed high (≥ 10⁵/cm²) when you need a monolayer tomorrow. Transfection protocols usually specify the target confluence at transfection time — work backwards from it using the doubling-time calculator.
Why calculate per cm² instead of per well?
Density per area is the transferable number: 2 × 10⁴ cells/cm² behaves the same in a 96-well well and a T-75, while 'cells per well' silently changes meaning between formats. Protocols written per area scale to any vessel with one multiplication — which is exactly what this calculator does.
Frequently asked questions
- How many cells for a 96-well plate at 1 × 10⁴ cells/cm²?
- 3,200 per well (0.32 cm² × 10⁴), so 3.1 × 10⁵ cells for a full plate before overage. Add ~10% extra volume for multichannel dead volume.
- Do all vendors' plates have the same growth area?
- Close but not identical — a '6-well' well is 9.6 cm² for Corning and 9.0–9.6 cm² elsewhere. For density-sensitive work use the area printed in your plate's certificate.
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