Hemocytometer Calculator

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Hemocytometer Cell Concentration Calculator

A hemocytometer is a specialized counting chamber used for counting cells or other microscopic particles in a known volume of fluid. It's a fundamental tool in biology, medicine, and biotechnology for applications like cell culture, blood cell counts, and microbial enumeration.

The chamber typically 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 specific dimensions. The most common type, the improved Neubauer chamber, has a central grid of 9 large squares, each 1 mm x 1 mm. The depth of the chamber is usually 0.1 mm.

The calculation of cell concentration involves counting cells within a specific number of these squares and then extrapolating that count to the original sample volume, accounting for any dilutions made.

How to Use This Calculator:

  1. Total Cells Counted: Enter the total number of cells you observed within your chosen counting squares.
  2. Number of Squares Counted: Specify how many individual squares (e.g., 4 large corner squares, 5 small central squares) you used for counting.
  3. Dilution Factor: If your sample was diluted before counting (e.g., 1 part sample + 9 parts diluent = 1:10 dilution), enter the dilution factor (e.g., 10). If no dilution, enter 1.
  4. Volume of Each Square (µL): This is critical. For a standard Neubauer hemocytometer:
    • A large square (1mm x 1mm x 0.1mm depth) has a volume of 0.1 µL.
    • A small square (0.2mm x 0.2mm x 0.1mm depth, found within the central large square) has a volume of 0.004 µL.
    Ensure you enter the correct volume corresponding to the type of square you counted.

The Formula:

Cell Concentration (cells/mL) = (Total Cells Counted / Number of Squares Counted) × Dilution Factor × (1000 / Volume of Each Square in µL)

The factor of 1000 converts the volume from microliters (µL) to milliliters (mL), as 1 mL = 1000 µL.

Example Calculation:

Let's say you counted 180 cells in 4 large corner squares of a hemocytometer. Your sample was diluted 1:5 before counting. The volume of each large square is 0.1 µL.

  • Total Cells Counted: 180
  • Number of Squares Counted: 4
  • Dilution Factor: 5
  • Volume of Each Square (µL): 0.1

Concentration = (180 / 4) × 5 × (1000 / 0.1)

Concentration = 45 × 5 × 10000

Concentration = 225 × 10000

Concentration = 2,250,000 cells/mL

(e.g., 0.1 for a large square, 0.004 for a small square)
function calculateHemocytometer() { var totalCells = parseFloat(document.getElementById('totalCells').value); var squaresCounted = parseFloat(document.getElementById('squaresCounted').value); var dilutionFactor = parseFloat(document.getElementById('dilutionFactor').value); var squareVolume_uL = parseFloat(document.getElementById('squareVolume_uL').value); var resultDiv = document.getElementById('result'); if (isNaN(totalCells) || isNaN(squaresCounted) || isNaN(dilutionFactor) || isNaN(squareVolume_uL) || totalCells < 0 || squaresCounted <= 0 || dilutionFactor <= 0 || squareVolume_uL <= 0) { resultDiv.innerHTML = 'Please enter valid positive numbers for all fields.'; return; } // Formula: Concentration (cells/mL) = (Total Cells Counted / Number of Squares Counted) * Dilution Factor * (1000 / Volume of Each Square in µL) var concentration = (totalCells / squaresCounted) * dilutionFactor * (1000 / squareVolume_uL); resultDiv.innerHTML = 'Estimated Cell Concentration: ' + concentration.toLocaleString() + ' cells/mL'; } // Initial calculation on page load with default values window.onload = calculateHemocytometer;

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