Cell Seeding Density Calculator
Seeding a plate is a two-step conversion. First turn your target density into a cell number: cells per well equals the density times the growth area (cells/cm² × cm²), or is the density itself when it is already quoted per well. Multiply by the number of wells to get the total cells you need. Then turn that cell number into a pipetting volume with C1V1 = C2V2 — divide the total cells by your stock concentration (corrected for viability) to get the volume of suspension to transfer, and make up the rest of each well with medium. Enter your density, vessel and counted stock below and the calculator returns cells per well, total cells, the suspension volume to add and the medium volume, flagging any case where the cell volume alone overfills the well.
Every seeding protocol quotes a target — 5,000 cells per well of a 96-well plate, or 2 × 10⁴ cells per cm² — and every experiment then asks the same question: how much of my counted suspension do I actually pipette? This page is part of the Cell Culture calculator set and it bridges those two numbers, converting a target density into a concrete volume plan.
The conversion runs through a cell number. A density is cells per unit area (or per vessel), so multiplying by the growth area of one well gives the cells that well must receive. Growth area is the number that trips people up: it is the manufacturer's stated culture surface, not the geometric footprint you would measure with calipers. For a standard 96-well plate it is about 0.32 cm², a 24-well about 1.9 cm², a 6-well about 9.6 cm², and tissue-culture flasks are named by their area (T25 = 25 cm², T75 = 75 cm²). If your target is already quoted per well, skip the area entirely.
With the per-well cell number and the well count you have the total cells required. The second step is a dilution in reverse. Your counted stock has a known concentration in cells/mL, so the volume that delivers the required cells is simply cells ÷ concentration — this is C1V1 = C2V2 rearranged to solve for V. If you measured viability with trypan blue, correct first: a stock counted at 1 × 10⁶ cells/mL but only 80% viable delivers live cells at 8 × 10⁵/mL, so you need more volume than the raw count suggests. Pair this tool with the cell counting calculator to get that stock concentration and the cell viability calculator for the live fraction.
Finally, the cells usually go in as a small volume topped up with medium. If you tell the calculator your intended working volume per well, it splits that into the cell-suspension volume and the medium to add. Watch for the case where the suspension alone exceeds the working volume — that means the stock is too concentrated to pipette accurately and should be diluted first, a step the dilution calculator handles. And if you are planning how long the seeded plate will take to reach confluence, carry the density into the population doubling time calculator.
Cell Seeding Density Calculator
How to use the cell seeding density calculator
Decide your target density and how it is quoted. If your protocol says cells/cm², keep the Density is expressed as selector on "cells per cm²" and enter the growth area of one well. If it says cells per well, choose "cells per well" and leave the area blank.
Enter the Target seeding density (e.g. 5000 for 5 × 10³ per well, or 20000 for 2 × 10⁴ per cm²).
If you chose per cm², fill in the Growth area per well using your vessel's stated area — 96-well ≈ 0.32, 24-well ≈ 1.9, 6-well ≈ 9.6, T25 = 25, T75 = 75.
Set the Number of wells / vessels you are seeding (leave 1 for a single flask or dish).
Enter the Stock concentration in cells/mL from your hemocytometer or automated count, and optionally the Viability % so only live cells are credited.
Optionally enter the Working volume per well in mL to get the medium-to-add split.
Press Calculate. The primary card is the total suspension volume to transfer; supporting cards show cells per well, total cells, the effective concentration and, if given, the medium per well. Heed any overfill warning.
Cell Seeding Density formula
Variables and units
| Symbol | Meaning | Unit |
|---|---|---|
| target density | Desired seeding density, per cm² or per well | cells/cm² or cells/well |
| growth area | Culture surface of one well or vessel | cm² |
| cells/well | Cells each well must receive | cells |
| wells | Number of wells, dishes or flasks seeded | — |
| total cells | cells/well × wells | cells |
| stock | Counted concentration of the suspension | cells/mL |
| viability | Fraction of stock that is live (optional) | % |
| Vstock | Suspension volume to transfer | mL |
How cell seeding density is calculated
- Convert the target density into cells per well: multiply by growth area if it is per cm², or take it directly if it is per well.
- Multiply cells per well by the number of wells to get the total cells required.
- Correct the stock concentration by viability (if given) to get the effective live-cell concentration.
- Divide total cells by the effective concentration to get the suspension volume to transfer; divide cells per well by it for the per-well volume.
- If a working volume per well is given, subtract the per-well cell volume to get the medium to add; warn if that goes negative (stock too concentrated).
Worked laboratory examples
Example 1 — 96-well plate, 5 × 10³ cells per well
Given: target density 5000 cells/well · wells 96 · stock 5 × 10⁵ cells/mL
- cells/well = 5000 (already per well).
- total cells = 5000 × 96 = 4.8 × 10⁵.
- Vstock = 4.8 × 10⁵ / 5 × 10⁵ = 0.96 mL of suspension across the plate.
- per well = 5000 / 5 × 10⁵ = 0.01 mL = 10 µL.
Result: 0.96 mL total (10 µL/well) of the 5 × 10⁵ cells/mL stock
Example 2 — Six-well plate at 1 × 10⁴ cells/cm²
Given: target density 10000 cells/cm² · growth area 9.6 cm²/well · wells 6 · stock 2 × 10⁵ cells/mL
- cells/well = 10000 × 9.6 = 9.6 × 10⁴.
- total cells = 9.6 × 10⁴ × 6 = 5.76 × 10⁵.
- Vstock = 5.76 × 10⁵ / 2 × 10⁵ = 2.88 mL.
Result: 2.88 mL total suspension (0.48 mL/well)
Example 3 — Viability correction
Given: target density 1 × 10⁶ cells/well (T75) · wells 1 · stock 1 × 10⁶ cells/mL · viability 50%
- total cells = 1 × 10⁶.
- effective concentration = 1 × 10⁶ × 0.50 = 5 × 10⁵ live cells/mL.
- Vstock = 1 × 10⁶ / 5 × 10⁵ = 2.0 mL — double the volume, because half the counted cells are dead.
Result: 2.0 mL of the 50%-viable stock delivers 1 × 10⁶ live cells
Example 4 — Medium to add, and the overfill trap
Given: cells/well 5000 · effective stock 5 × 10⁵ cells/mL · working volume 0.1 mL/well
- cell volume per well = 5000 / 5 × 10⁵ = 0.01 mL.
- medium per well = 0.1 − 0.01 = 0.09 mL.
- If instead the stock were 5 × 10³ cells/mL, the cell volume would be 1.0 mL/well — far over the 0.1 mL working volume, so the calculator warns you to dilute the stock or raise the volume.
Result: 0.09 mL medium/well at a workable stock; a negative balance flags an over-concentrated suspension
Want the reasoning behind the numbers? Read How to Calculate Cell Seeding Density.
How to interpret the result
The total suspension volume is what you pipette from your counted tube; the per-well volume is what each well receives. For a many-well plate, prepare a master mix of cells in medium slightly larger than the calculated total to cover pipetting and dead volume.
Cells per well versus cells per cm² are two views of the same target. Multiplying a per-cm² density by the vessel area moves you between them, so a protocol written for one plate can be translated to another by area.
A viability below 100% inflates the required volume — the calculator credits only live cells to the stock. This is the single most common reason a seeded plate comes out under-density: people pipette as if every counted cell were alive.
If the medium-to-add number is negative, do not just "add less medium." The stock is too concentrated to dispense the tiny cell volume accurately; dilute it to a workable concentration first, then re-run.
Assumptions
- The stock is freshly counted, homogeneous and free of clumps, so the pipetted volume carries the stated concentration.
- Growth area values entered are the manufacturer's stated culture surface for the vessel.
- Viability, when entered, reflects the live fraction of the counted stock at the time of seeding.
- The working volume per well is the final intended volume of cells plus medium.
- Attachment/plating efficiency is not modelled — the calculator assumes every seeded live cell is delivered to the well.
Limitations
- Chooses volumes for a target density; it does not recommend the density appropriate to your assay or cell line.
- Growth areas vary by vendor and plate format — always use the stated area, not a generic guess.
- Does not account for plating efficiency, differential attachment or cells lost to tubing and dead volume.
- Assumes a single uniform stock; a multi-dilution or serial-passaging plan needs the dilution tools alongside it.
Common mistakes
- Multiplying a target that is already per well by the growth area, double-counting the area factor.
- Ignoring viability and pipetting as if the raw count were all live cells, yielding an under-density plate.
- Using the geometric well footprint instead of the stated growth area, especially for treated or irregular surfaces.
- Not making a master mix with excess volume, so the last wells of a plate run short.
- Adding the cell volume on top of a full working volume instead of subtracting it, overfilling the well.
FAQ
What is seeding density?
How do I convert cells/cm² to cells/well?
Why correct the stock for viability?
What if the cell volume is larger than the well volume?
How does this connect to confluence timing?
Scientific Sources
- Wikipedia — Cell culture (seeding density and passaging practice) · Tier 3 source
- Wikipedia — Hemocytometer (cell concentration feeding the seeding plan) · Tier 3 source
External links open in a new tab and carry rel="nofollow". We cite primary references (NIST, NIH/NCBI, peer-reviewed papers) and established manufacturer technical documentation (NEB, Thermo Fisher, Promega, IDT). Calculated results are estimates; your protocol and manufacturer guidance take precedence.
Last reviewed: 2026-09 · Method version: 1.0