Cell Seeding Density Calculator
Reproducible cell culture starts with seeding the right number of cells. Given a target density in cells per square centimetre, the growth area of each well, and your stock concentration, this calculator works out how many cells go in each well, the total cells you need across the plate, and the volume of stock and fresh medium to combine. Enter your plate's actual per-well growth area and a live-cell stock concentration for accurate, repeatable seeding.
Seeding density formula
Cells per well = target density * area per well
Total cells = cells per well * number of wells
Stock volume = total cells / stock concentration
Total plating volume = wells * volume per well
Fresh medium = total plating volume - stock volume
Use your plate's actual per-well growth area and a live-cell stock concentration. The stock volume carries the cells; the rest of the plating volume is fresh medium.
Seeding tips
- Match seeding density to your cell line and the confluence you want at assay time.
- Mix the cell suspension well before pipetting so the concentration is uniform.
- Use viable-cell counts; dead cells should not count toward the seeding number.
- Per-well growth area differs slightly by manufacturer; use the value on your plate's datasheet.
- Prepare a small excess of suspension to cover pipetting loss across many wells.
Seeding density: frequently asked questions
What is cell seeding density?
Seeding density is the number of cells placed per unit growth area or per well at the start of a culture. It is usually expressed as cells per square centimetre or cells per well. The right density keeps cells healthy: too sparse and they grow slowly or fail to reach confluence, too dense and they over-confluence and stress before an assay.
How do I convert cells per cm2 to cells per well?
Multiply the target density in cells per square centimetre by the growth area of one well in square centimetres. For example, a standard flat-bottom 96-well plate well has a growth area near 0.32 cm2, while a 6-well plate well is near 9.6 cm2. Enter your plate's actual per-well area, since it varies slightly by manufacturer.
How much cell stock do I need?
Total cells needed equals cells per well times the number of wells. Divide that by your stock concentration in cells per millilitre to get the stock volume to add. The remaining volume up to your per-well plating volume times the well count is made up with fresh medium.
Why does seeding density matter for an experiment?
Consistent seeding density makes results reproducible. Cell behaviour, confluence at assay time, drug response, and signalling all depend on density. Seeding at the same density across plates and days controls a major source of variability, which is why protocols specify an exact cells per cm2 figure.
Do I need to account for viability?
Yes. If your stock concentration is a total count, multiply by the viable fraction to get live cells, or count only live cells with a viability dye. Seeding by total count when viability is low will under-seed the live population. This calculator uses the concentration you provide, so enter a live-cell concentration for accuracy.
Official sources
- National Center for Biotechnology Information: NCBI cell culture methods literature.
- National Institute of Standards and Technology: NIST measurement and units.
Reviewed by the CalculatorHub team, edited by James Graham, 17 June 2026. See our methodology.