Haemocytometer Cell Concentration Calculator
Use this calculator to determine the cell concentration (cells/mL or cells/µL) of your sample after counting cells using a haemocytometer. This tool accounts for the number of cells counted, the number of squares observed, any sample dilution, and the specific dimensions of your haemocytometer chamber.
Enter the total number of cells you counted across all observed squares.
Specify how many large squares (e.g., 1×1 mm squares) were used for counting. Common values are 5 (for WBCs) or 9 (for general cell counts).
If your sample was diluted (e.g., 1:10 dilution), enter the dilution factor (e.g., 10). Enter '1' if the sample was not diluted.
The depth of the haemocytometer chamber. Standard depth is 0.1 mm.
The side length of one large square on the haemocytometer grid. Standard is 1.0 mm.
Understanding Haemocytometer Cell Counting
A haemocytometer is a specialized counting chamber used for counting cells (such as blood cells, bacteria, sperm, or cultured cells) in a liquid sample. It consists of a thick glass slide with a rectangular indentation that creates a precisely known volume when a coverslip is placed over it. The bottom of this chamber is etched with a grid of perpendicular lines, forming squares of known area.
How a Haemocytometer Works
The most common type of haemocytometer, the improved Neubauer chamber, has a central ruled area. This area is typically 3 mm x 3 mm, divided into nine large 1 mm x 1 mm squares. Each of these large squares is further subdivided. For example, the four corner large squares and the central large square are often used for counting. The depth of the chamber is usually 0.1 mm.
By counting the cells within a specific number of these squares and knowing the volume of those squares, you can calculate the concentration of cells in the original sample.
The Calculation Formula
The general formula for calculating cell concentration using a haemocytometer is:
Cells/mL = (Total Cells Counted / Total Volume Counted in mL) × Dilution Factor
Where:
- Total Cells Counted: The sum of cells observed in all the chosen squares.
- Total Volume Counted in mL: This is derived from the number of squares counted, the area of each square, and the chamber depth. For a standard large square (1mm x 1mm) and a chamber depth of 0.1mm, the volume of one large square is 0.1 mm³. Since 1 mL = 1000 mm³, one large square has a volume of 0.0001 mL.
- Dilution Factor: If your sample was diluted before counting (e.g., 1 part sample + 9 parts diluent = 1:10 dilution), you multiply by the dilution factor (e.g., 10). If no dilution was performed, the factor is 1.
Example Scenario
Let's say you are counting white blood cells (WBCs) and perform a 1:10 dilution of your blood sample. You count cells in 5 large squares (the four corner squares and the central square) of a standard haemocytometer. You find a total of 200 cells.
- Total Cells Counted: 200
- Number of Large Squares Counted: 5
- Dilution Factor: 10
- Chamber Depth: 0.1 mm
- Side Length of One Large Square: 1.0 mm
Using the calculator:
- Volume of one large square = 1.0 mm * 1.0 mm * 0.1 mm = 0.1 mm³
- Total volume counted = 5 squares * 0.1 mm³/square = 0.5 mm³
- Convert total volume to mL: 0.5 mm³ / 1000 mm³/mL = 0.0005 mL
- Cell Concentration = (200 cells / 0.0005 mL) * 10 = 400,000 * 10 = 4,000,000 cells/mL
- In µL: 4,000,000 cells/mL / 1000 µL/mL = 4,000 cells/µL
This calculator automates these steps, providing quick and accurate results for your cell counting needs.