How do you calculate cell seeding density?
Decide the cells per well, either directly or as cells per cm² x the well's growth area. The seeding suspension then needs cells per well ÷ volume per well cells per mL. Multiply cells per well by the number of wells, plus a margin of around 10% for pipetting loss, and divide by your counted concentration to get the volume of cell suspension; top it up with medium to the total volume.
Worked example: 10,000 cells per well in 100 µL across 96 wells with 10% extra, from a suspension of 1,200,000 cells/mL. That is 105.6 wells' worth, 1,056,000 cells, so use 0.88 mL of suspension and 9.68 mL of medium for 10.56 mL at 100,000 cells/mL.
What are the growth areas of standard plates?
Typical values from Thermo Fisher's Useful Numbers for Cell Culture: 6-well 9.6 cm², 12-well 3.5 cm², 24-well 1.9 cm², 48-well 1.1 cm², 96-well 0.32 cm² and 384-well 0.084 cm². Other manufacturers' plates differ slightly, so the calculator lets you edit the area and the volume per well.
How many cells should I seed per well?
It depends on the cell line, how fast it grows, how long the assay runs and how confluent the wells should be at the readout, so there is no single right number. Run a growth curve for each line and set the density from it. Count with the Hemocytometer and Cell Viability Calculator and use the live-cell concentration here.
Frequently asked questions
How many cells should I seed in a 96-well plate?
It varies with the cell line and the assay length, so set it from a growth curve. The calculator converts whatever density you choose into a recipe for the plate.
What is the surface area of a well in a 96-well plate?
About 0.32 cm² for a standard flat-bottom 96-well plate (Thermo Fisher's Useful Numbers for Cell Culture). Check your plate's datasheet.
Should I use the total or the live cell count?
The live (viable) cell concentration, so the wells receive the number of living cells you intend.
Why add extra volume?
Pipetting and reservoir dead volume lose some suspension. A margin of about 10% avoids running short on the last wells.
What if my suspension is too dilute?
If the cell suspension is weaker than the seeding concentration, the calculator says so. Spin the cells down, resuspend in less medium and count again.
Is anything I enter saved or sent?
No. The calculator runs in your browser. Nothing you type is saved, sent to BioBridgeX or added to the page address, and analytics never see your numbers.
Related free tools
- Hemocytometer and Cell Viability Calculator: Percent viability, live cells/mL and total live cells from a trypan blue hemocytometer count.
- 96 and 384 Well Plate Layout Planner: Lay out compounds, concentrations, replicates and controls on 96- or 384-well plates and count the plates.
- In Vitro Assay and Screening Planner: Assay type, cell models, compounds, concentration series, controls, replicates and readout as an organized assay plan.
- All lab calculators and every free tool on BioBridgeX.
Sources
Check every result before use. Formulas assume ideal conditions; follow your validated lab procedures and the reagent supplier's instructions. Facts on this page last checked 27 October 2026.
Compare quotes from vetted In Vitro Pharmacology suppliers on BioBridgeX. Free for buyers. Planning is optional: these tools work without an account, and nothing you enter is shared.