The neutrophil to lymphocyte ratio compares innate immune response (neutrophils) to adaptive immune response (lymphocytes) as a single number. It's computed automatically from the CBC differential.
The N:L ratio is emerging as one of the most useful prognostic markers from standard bloodwork. Elevated ratios indicate systemic inflammation and correlate with increased mortality, cardiovascular events, and worse outcomes across many chronic diseases. Optimal ratios fall between 1 and 3; values above 3 reflect meaningful inflammatory stress. It's particularly valuable as a longevity marker because it captures chronic inflammation at a level that individual WBC components may miss. Acute stress transiently raises the ratio, so consistent fasting-state measurements give the most interpretable trends.
Optimal Neutrophil:Lymphocyte Ratio: 1-2 ratio.
Typically re-tested every 8 weeks.
Calculators that use Neutrophil:Lymphocyte Ratio: