Physiology Lab

WBC Count Calculator

Total leucocyte count from an improved Neubauer hemocytometer — cells counted, squares, depth and dilution, worked step by step.

Sample

Sample / subject ID (optional)

Printed on the lab result card.

Count and dilution

The total cells in all the squares you counted, and the dilution of the blood.

Quick setup

Number of cells counted

cells

Total across every square counted.

Dilution factor (e.g. 20 for 1:20)

1:20 means 1 volume of blood in 20 volumes of suspension.

Common dilutions

Counting squares

Which squares you counted, and the depth of your chamber. Check both against your manual.

Square type

Number of squares counted

Standard WBC count: 4 large corner squares.

Chamber depth

Improved Neubauer: 0.1 mm.

Improved Neubauer ruling: nine 1 mm large squares, the central one divided into 25 medium squares, with the counted squares shaded blue

Live chamber readout

Area counted = n × a = 4 × 1 mm² = 4 mm²

Volume = 4 mm² × 0.1 mm = 0.4 mm³

Reference range (optional, educational)

No range is built in. Enter the one from your manual to add a comparison to the lab card.

Low limit

cells/mm³

High limit

cells/mm³

Laboratory calculation card

Enter the cells counted and the dilution factor. The squares and depth start at the standard WBC setup.

Area counted (mm²) = number of squares × area of one square

Volume counted (mm³) = area counted × chamber depth

WBC (cells/mm³) = cells counted × dilution factor ÷ volume counted

Standard WBC count: 4 large squares × 1 mm² × 0.1 mm = 0.4 mm³. The calculation factor is 20 ÷ 0.4 = 50, so 150 cells counted gives 150 × 50 = 7,500 cells/mm³.

1 mm³ = 1 µL; cells/µL × 10⁶ = cells/L; 7,500/µL = 7.5 × 10⁹/L

Manual factor mode skips the area and depth: count = cells counted × factor. The factor already equals dilution ÷ volume, so a manual's factor of 50 is the same arithmetic done in advance.

Common questions

Count cells touching the top and left boundary lines of each square and ignore those touching the bottom and right lines (or the other way round — just be consistent). Otherwise a cell lying on a shared line is counted in two neighbouring squares.

Red cells outnumber white cells roughly 700 to 1 and would hide them completely. Türk's fluid contains dilute acetic acid, which haemolyses the red cells, and gentian violet, which stains the leucocyte nuclei so they stand out against the empty background.

There are only a few thousand white cells per mm³ but several million red cells. A low dilution and a large counting area (4 mm²) give enough white cells to count accurately; red cells need a ten-fold higher dilution and a far smaller area, or they would be too crowded to count.

Both, if they match what you actually did. The factor is always dilution ÷ volume counted, so it changes with the number and size of squares and with the dilution. Use Manual factor mode to enter your manual's factor directly, or enter its squares and dilution in Standard formula mode.

Yes. Türk's fluid does not destroy nucleated red cells, and in the chamber they look like leucocytes, so they are counted as white cells. If a stained blood film shows nucleated red cells, laboratories correct the count: corrected WBC = counted WBC × 100 ÷ (100 + nucleated RBCs per 100 WBCs).

About the hemocytometer WBC count

A hemocytometer is a thick glass slide with a precisely ruled grid and a chamber of known depth under the coverslip. Because both the area of each square and the depth are known, the cells you see in a set of squares sit in a known volume — and dividing by that volume, then multiplying by the dilution, gives cells per mm³ of blood.

The improved Neubauer ruling is 3 mm × 3 mm, split into nine large squares of 1 mm². The four corner squares, divided into 16, are used for white cells. The central square is divided into 25 medium squares (0.04 mm²), each into 16 smallest squares (0.0025 mm²), for red cells and platelets.

The depth matters as much as the area: at the standard 0.1 mm, 1 mm² holds 0.1 mm³. A chamber of a different depth, or a coverslip that is not seated flat, changes the volume and every result with it.

The standard WBC count

Dilute blood 1:20 in Türk's fluid, which lyses red cells and stains leucocyte nuclei

Count the four corner large squares: 4 mm² × 0.1 mm = 0.4 mm³

Factor = 20 ÷ 0.4 = 50, so cells/mm³ = cells counted × 50

Sources of error

Uneven filling — overfilling, air bubbles or a dry chamber change the volume

Cells on boundary lines counted twice — count the top and left lines only

Clumped cells, from poor mixing or a clotted sample

Pipetting and dilution errors, which are multiplied by the dilution factor

Too few cells counted — the Poisson error is about ±1/√N

Reference ranges vary with age, sex and laboratory. This tool does not assert a normal range; it compares against one only if you enter it, for educational purposes.

Prepared by the PharmaWallah student team. Verify results with your textbook or instructor. Report an error · Editorial policy