PonyatnoHow it's calculated
NLR = neutrophils ÷ lymphocytes. Both are absolute counts in ×10⁹/L. NLR is rounded to two decimals.
If you enter platelets, two more indices are calculated: PLR = platelets ÷ lymphocytes and SII = platelets × neutrophils ÷ lymphocytes (systemic immune-inflammation index). Both are rounded to whole numbers.
If your report shows only percentages, get the absolute count from the white cell count: absolute = WBC × % ÷ 100. For example, WBC 6.0 and lymphocytes 30% → 6.0 × 30 ÷ 100 = 1.8 ×10⁹/L. For NLR itself, percentages give the same answer (the WBC cancels out), but PLR and SII need true absolute counts.
The typical range comes from Forget et al. (2017) in healthy adults: NLR from 0.78 to 3.53. There is no accepted normal range for PLR or SII, so the calculator shows them without a rating.
What to know
What NLR shows
Neutrophils are the first responders to bacterial infection, injury and stress, while lymphocytes tend to leave the bloodstream during acute stress. So the ratio shifts quickly whenever the body is under strain, which is why it is described as a marker of physiological stress (Zahorec, 2021).
In research, a high NLR is linked to a more severe course of many illnesses. But it is an extra clue for a doctor, not a test that gives a diagnosis on its own.
Why the ratio is easy to misread
NLR is non-specific: it rises with infection, but also after a sleepless night, a marathon or surgery, with steroids such as prednisone or dexamethasone, with smoking and in pregnancy. It changes within hours, so a single value says little.
The Forget range was measured in adults; children have different ratios. Some people naturally have lower neutrophil counts (common, for example, in people of African ancestry), so their NLR is lower with no illness at all.
Published PLR and SII cut-offs vary widely and are tied to specific diseases and patient groups. They should not be applied to an individual result.
Using the result in practice
It is most useful to compare your own values over time, taken under similar conditions: in the morning, without an acute illness or a hard workout the day before. If your NLR is clearly higher than usual and stays that way, show the results to your doctor along with how you feel.
This calculator is a reference tool, not a diagnosis. Laboratory ranges differ, and the result depends on your health, medicines and other tests. Discuss it with your doctor.
FAQ
What is a normal NLR?
In healthy adults in the Forget (2017) study it was usually between 0.78 and 3.53. Treat this as a guide rather than a strict normal range: stress, exercise and medicines all move it.
How do I calculate NLR if my blood test only shows percentages?
For NLR you can simply divide the neutrophil percentage by the lymphocyte percentage — the result is the same. To enter absolute counts (needed for PLR and SII), multiply the WBC by the percentage and divide by 100.
Why is my NLR high if I feel fine?
Stress, poor sleep, hard training, smoking, steroids, pregnancy or a recent cold can all raise it. Usually the test is repeated when you are well rested to see whether the change persists.
What are PLR and SII, and what are their normal values?
PLR is platelets divided by lymphocytes; SII is platelets × neutrophils ÷ lymphocytes. They are studied as inflammation markers, but there is no accepted normal range — cut-offs differ a lot between studies.
Can NLR tell a bacterial infection from a viral one?
NLR is higher on average in bacterial infections, but the ranges overlap. It is not reliable on its own — a doctor decides based on examination and other tests.
Sources
Formulas and cut-offs follow clinical guidelines — see sources below.
- Forget P et al. What is the normal value of the neutrophil-to-lymphocyte ratio? BMC Res Notes. 2017;10:12.
- Zahorec R. Neutrophil-to-lymphocyte ratio, past, present and future perspectives. Bratisl Lek Listy. 2021;122(7):474–488.