The neutrophil-lymphocyte ratio (NLR) is a simple lab-derived ratio — the absolute neutrophil count divided by the absolute lymphocyte count — used as a general marker of systemic inflammation. This calculator computes NLR directly from ANC and ALC, or derives those counts from a total WBC count and CBC differential percentages.

How the neutrophil-lymphocyte ratio works

NLR combines two arms of the immune system into one number: neutrophils (innate immunity, first responders to acute stress, injury, and infection) in the numerator, and lymphocytes (adaptive immunity) in the denominator. During an acute inflammatory or stress response, neutrophil counts tend to rise while lymphocyte counts tend to fall, so the ratio rises faster than either count alone.

NLR = ANC ÷ ALC, where both counts are absolute values in cells/µL. It has been studied across a wide range of settings — infection severity, sepsis, cardiovascular disease, surgical stress, and oncology — as a low-cost, widely available marker calculated from a routine complete blood count with differential.

Inputs and what they mean

ANC (absolute neutrophil count) and ALC (absolute lymphocyte count) are both reported directly on most CBC-with-differential lab panels, in cells/µL.

If your lab report instead gives a total WBC count (commonly in ×10³/µL) alongside percentage differential values, use the From Counts tab: ANC and ALC are derived by multiplying WBC by each percentage, then NLR is computed from the derived counts.

Limits and edge cases

NLR is a general, nonspecific marker — not a diagnostic test for any single condition. Published "elevated" cutoffs vary widely, from roughly 3 up to over 5 or more, depending on the population and condition studied; there is no single universal threshold. Medications, recent exercise, acute stress, corticosteroid use, and many acute or chronic illnesses can all shift neutrophil and lymphocyte counts independent of the condition being evaluated. A single NLR reading should prompt clinical correlation and, where relevant, trending over time — not stand alone as a diagnosis.