How to Calculate Absolute Eosinophil Count
Absolute eosinophil count (AEC) is the actual number of eosinophils — a type of white blood cell involved in allergic reactions and parasite defense — per microliter of blood. A standard complete blood count (CBC) with differential reports eosinophils only as a percentage of total white blood cells, so AEC must be calculated: AEC = WBC × (Eos% ÷ 100), where WBC is the total white blood cell count and Eos% is the eosinophil percentage from the differential. This calculator performs that conversion and classifies the result against standard hematology reference ranges.
How the calculation works
Enter your total WBC count (most labs report this as x10³/µL, also written K/µL, which is numerically identical to the SI unit x10&sup9;/L) and the eosinophil percentage from the differential portion of the CBC. The calculator converts WBC to cells per microliter if needed, then multiplies by the eosinophil percentage divided by 100. For example, a WBC of 7.0 x10³/µL with 3% eosinophils gives 7,000 × 0.03 = 210 cells/µL, well within the normal range.
Interpreting your result
Most clinical laboratories define a normal AEC as 0-500 cells/µL (0-0.5 x10&sup9;/L) in adults. Eosinophilia is generally graded as mild (500-1,500 cells/µL), moderate (1,500-5,000 cells/µL), or severe (above 5,000 cells/µL). Common causes of elevated counts include allergic disease and asthma, medication reactions, parasitic infections, skin conditions such as eczema, and autoimmune or eosinophilic disorders; a persistently low or absent count (eosinopenia) is most often linked to acute illness, stress, or corticosteroid use and is rarely significant on its own.
When to consult a professional
An isolated elevated or low eosinophil count is not a diagnosis. Sustained counts above 1,500 cells/µL, or any result paired with symptoms such as rash, wheezing, unexplained weight loss, or gastrointestinal complaints, should be reviewed by a physician, who can order additional testing to identify the underlying cause. This calculator is an educational tool for understanding CBC results, not a substitute for professional medical advice.