What is a normal SII?

In the Rotterdam Study of 8,711 adults aged 45 and over, the average was 459 and 95% had an SII between 189 and 1,168. Cut-offs such as 330 come from cancer studies and don’t apply to a healthy person.

How do you calculate the systemic immune-inflammation index?

Multiply platelets by neutrophils and divide by lymphocytes, all absolute counts in ×10⁹/L. Platelets 210, neutrophils 3.6 and lymphocytes 2.0 give 210 × 3.6 ÷ 2.0 = 378.

What does a high SII mean?

That neutrophils and platelets are high relative to lymphocytes, the pattern of an active inflammation or infection. It was introduced to predict outcomes in liver cancer and is mostly used in research. A doctor reads it with the full blood count and your symptoms.

Systemic immune-inflammation index (SII) calculator

Short answer: SII is platelets × neutrophils ÷ lymphocytes, all absolute counts in ×10⁹/L from a full blood count. In 8,711 healthy adults aged 45 and over it averaged 459, and 95% fell between 189 and 1,168. Higher values go with inflammation; it is a research marker, not a diagnosis.

Free calculator

SII calculator (systemic immune-inflammation index)

SII = platelets × neutrophils ÷ lymphocytes (absolute counts)

Sources: Hu B, Yang XR, Xu Y, et al. Systemic immune-inflammation index predicts prognosis of patients after curative resection for hepatocellular carcinoma. Clin Cancer Res 2014;20(23):6212-6222.

Unit

Platelets

×10⁹/L

×10⁹/L is the same number as ×10³/µL or K/µL

Neutrophils, absolute count

×10⁹/L

The count, not the %. Sometimes printed as ANC or NEU#

Lymphocytes, absolute count

×10⁹/L

The count, not the %. Sometimes printed as ALC or LYM#

Your result

Enter the numbers from your lab report to see your result.

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A pointer, not a diagnosis. Talk to a doctor about your result, and sooner if you feel unwell.

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How to read the result

Below 189< 189Lower than in 95% of healthy adults in a large study. On its own it has no known meaning; look at the three counts on your report.
189 to 1,167189 – 1,168In the range of 95% of healthy adults in a large population study.
1,168 or above≥ 1,168Higher than in 95% of healthy adults. It rises with infection and inflammation of any kind; on its own it does not say what. If you feel unwell or it stays high, talk to a doctor.

Your lab’s range

SII is not printed on lab reports and has no clinical cut-off for a healthy person. The bands are the 95% reference range of 8,711 adults aged 45 and over in the Rotterdam Study (average 459, range 189–1,168). Cancer studies use their own cut-offs, such as 330 in the paper that introduced it, which do not apply to a healthy person.

How it is worked out

SII = platelets × neutrophils ÷ lymphocytes (absolute counts)

Sources

Hu B, Yang XR, Xu Y, et al. Systemic immune-inflammation index predicts prognosis of patients after curative resection for hepatocellular carcinoma. Clin Cancer Res 2014;20(23):6212-6222.
Fest J, Ruiter R, Ikram MA, Voortman T, van Eijck CHJ, Stricker BH. Reference values for white blood-cell-based inflammatory markers in the Rotterdam Study: a population-based prospective cohort study. Sci Rep 2018;8:10566.

The markers it uses

Platelet Count Neutrophils Absolute Neutrophil Count Lymphocytes Absolute Lymphocyte Count

Questions

What is a normal SII?: In the Rotterdam Study of 8,711 adults aged 45 and over, the average was 459 and 95% had an SII between 189 and 1,168. Cut-offs such as 330 come from cancer studies and don’t apply to a healthy person.
How do you calculate the systemic immune-inflammation index?: Multiply platelets by neutrophils and divide by lymphocytes, all absolute counts in ×10⁹/L. Platelets 210, neutrophils 3.6 and lymphocytes 2.0 give 210 × 3.6 ÷ 2.0 = 378.
What does a high SII mean?: That neutrophils and platelets are high relative to lymphocytes, the pattern of an active inflammation or infection. It was introduced to predict outcomes in liver cancer and is mostly used in research. A doctor reads it with the full blood count and your symptoms.

More calculators for the same system

NLR calculator ANC calculator Mentzer index calculator Sehgal index calculator PLR calculator (platelet-to-lymphocyte ratio)

All blood test calculators

A pointer, not a diagnosis. Talk to a doctor about your result, and sooner if you feel unwell. Reference ranges are general-population guidance compiled from common clinical laboratories, not a diagnosis. Lab-to-lab ranges differ. Always read your results with your doctor.