Which blood counts does SII require?

SII uses absolute platelet, neutrophil, and lymphocyte counts from a reasonably contemporaneous complete blood count and differential. Percentages cannot be mixed with absolute counts.

How are blood-count units handled?

Each input can use ×10³/µL, the numerically equivalent ×10⁹/L, or cells/µL. The calculator converts all three values to ×10⁹/L before applying the formula.

Is there one normal SII range?

No. SII was developed in a specific cancer population and later studies use different diseases, timings, treatments, outcomes, and cutoffs. The result does not diagnose inflammation, infection, cancer, or prognosis.

Educational reference only. Not a diagnostic tool. See full disclaimer.

HematologySII

Systemic Immune-Inflammation Index Calculator

Calculate SII from compatible absolute platelet, neutrophil, and lymphocyte counts.

Content updated: July 18, 2026View sources

Platelet count

Absolute neutrophil count

Absolute lymphocyte count

Systemic Immune-Inflammation Index

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Research-derived absolute-count index; no universal category is assigned

Normalized P/N/L: — / — / — ×10⁹/L

About

Systemic Immune-Inflammation Index (SII) combines absolute platelet, neutrophil, and lymphocyte counts. It was developed as a research prognostic index in hepatocellular carcinoma and has since been studied in many unrelated populations; it is not a general diagnostic inflammation test.

Formula

SII = platelet count × absolute neutrophil count ÷ absolute lymphocyte count

All counts are normalized to ×10⁹/L before calculation

Interpretation

What the result represents: A derived index combining three contemporaneous absolute blood counts.

Input units: Each absolute count may use ×10³/µL, numerically equivalent ×10⁹/L, or cells/µL. Percent differential values are not accepted.

Worked example: Platelets 250, neutrophils 4, and lymphocytes 2 in ×10⁹/L gives SII = 500 ×10⁹/L.

Applicable population: Research contexts with a complete blood count and absolute differential collected at the same time. Study-specific populations and outcomes must be considered.

Interpretation limitations: Infection, inflammation, cancer, medicines, hematologic conditions, treatment, stress, and sampling time can change each component. Published thresholds vary widely; this result does not assign inflammation, infection, cancer, cardiovascular risk, or prognosis.

References

FAQ

Related Calculators

NLR

Calculate neutrophil-to-lymphocyte ratio from absolute counts or percentages.

PLR

Calculate platelet-to-lymphocyte ratio from compatible absolute counts.

ANC

Calculate absolute neutrophil count from CBC differential.

Disclaimer

Educational and informational reference only. Not intended to replace professional medical advice, diagnosis, treatment, or independent verification.