Systemic Immune-Inflammation Index Calculator
Calculate the Hu 2014 SII from matched absolute platelet, neutrophil, and lymphocyte counts with exact unit normalization.
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Formula and medical content are based on the references listed on this page. See sources, About, and Sources and Review Process.
About
Formula
Interpretation
What the result represents
A derived index combining three contemporaneous absolute blood counts. The output retains ×10⁹/L when the normalized platelet and differential counts use that scale.
Input units
Each count may use ×10³/µL, the numerically equivalent ×10⁹/L, or cells/µL. Percent differential values are not accepted.
Worked example — not a category
Platelets 250, neutrophils 4, and lymphocytes 2 in ×10⁹/L gives 250 × 4 ÷ 2 = 500 ×10⁹/L.
Applicable population and evidence context
Hu 2014 developed SII in adults with hepatocellular carcinoma after curative resection; its 330 cutoff is specific to that cohort and endpoint. Luo's 142–804 interval is specific to a healthy-adult study, not a universal reference range. Children have age-specific SII distributions, and SII can vary by trimester and pregnancy state. Values from pediatric, pregnancy, healthy-adult, and disease studies are not interchangeable.
Interpretation limitations
Review the source CBC/differential, laboratory intervals, collection time, medicines, treatment, infection/inflammation, hematologic conditions, immune status, and applicable pathway. This page applies no dynamic interval or category to a result. SII cannot diagnose or exclude disease, predict one person’s outcome, or select testing, referral, medication, or treatment.
References
- Hu B, et al. Systemic immune-inflammation index predicts prognosis of patients after curative resection for hepatocellular carcinoma. Clin Cancer Res. 2014;20(23):6212–6222. PMID 25271081. DOI 10.1158/1078-0432.CCR-14-0442.
- Luo H, et al. Normal Reference Intervals of NLR, PLR, LMR, and SII in Healthy Adults: a Large Multi-Center Study from Western China. Clin Lab. 2019;65(3). PMID 30868857. DOI 10.7754/Clin.Lab.2018.180715.
- Establishment of age-specific reference intervals for peripheral blood SII, NLR, PLR, and LMR in healthy children. BMC Immunology. 2026;27:22. PMID 41549237. DOI 10.1186/s12865-025-00797-2.
- Bai YY, et al. Reference intervals of systemic immune-inflammation index, neutrophil-to-lymphocyte ratio, lymphocyte-to-monocyte ratio, and platelet-to-lymphocyte ratio during normal pregnancy in China. Eur Rev Med Pharmacol Sci. 2023;27(3):1033–1044. PMID 36808350. DOI 10.26355/eurrev_202302_31199.
- Walzik D, Joisten N, Zacher J, Zimmer P. Transferring clinically established immune inflammation markers into exercise physiology: focus on NLR, PLR and SII. Eur J Appl Physiol. 2021;121(7):1803–1814. PMID 33787989. PMCID PMC8192383. DOI 10.1007/s00421-021-04668-7.
- Wang H, Nie H, Bu G, Tong X, Bai X. Systemic immune-inflammation index and the risk of all-cause, cardiovascular, and cardio-cerebrovascular mortality in the general population. Eur J Med Res. 2023;28:575. PMID 38066657. PMCID PMC10709886. DOI 10.1186/s40001-023-01529-1.
- Ye F, Jin J, Dai J. The association between systemic immune-inflammation index and short-term functional outcome after aneurysmal subarachnoid hemorrhage: a meta-analysis. Neurosurg Rev. 2025. PMID 40016496. DOI 10.1007/s10143-025-03300-y.
FAQ
Multiply the absolute platelet count by the absolute neutrophil count, then divide by the absolute lymphocyte count after all three values are normalized to ×10⁹/L.
SII uses absolute platelet, neutrophil, and lymphocyte counts from the same CBC and differential time point. Percentages cannot replace absolute counts.
Each input can use ×10³/µL, the numerically equivalent ×10⁹/L, or cells/µL. The calculator converts all three values exactly to ×10⁹/L before applying the formula.
Each count can change over time. Combining unrelated reports can create an index that never represented one biologic time point.
Keeping the same number after a unit change could silently reinterpret it on a different scale. Clearing requires the source report to be checked again.
Either numerator may be zero mathematically and produces an index of zero when the lymphocyte denominator is positive. The source result and its clinical urgency still require review.
Lymphocytes form the denominator. Division by zero is undefined, so SII cannot be calculated from a zero or missing absolute lymphocyte count.
Hu and colleagues developed SII in adults with hepatocellular carcinoma after curative resection. The original study context is not a general-population diagnostic framework.
No. The 330 ×10⁹/L cutoff was selected for the original hepatocellular-carcinoma cohort and endpoints. It must not be applied automatically to unrelated populations or outcomes.
Luo and colleagues reported 142–804 in one healthy-adult study population. It is not interchangeable with disease-study values, pediatric distributions, pregnancy data, or a laboratory-specific interval, and this page does not apply it to an individual result.
No. Pediatric SII distributions are age-specific. This calculator does not apply pediatric or adult dynamic intervals, categories, diagnoses, or treatment rules to a result.
Yes. Pregnancy SII can vary by trimester and pregnancy state. Pregnancy, pediatric, healthy-adult, and disease-study values are not interchangeable, and this page does not apply a pregnancy-specific interval.
No. Healthy-population and disease studies differ by age, sex, population, disease, timing, treatment, outcome, laboratory context, and cutoff. This page reports arithmetic only; it does not output low, normal, high, positive, or negative categories.
No. SII is nonspecific and cannot establish or exclude inflammation, infection, sepsis, or another diagnosis.
No. Research associations do not turn one arithmetic result into a cancer diagnosis or an individualized outcome prediction.
Yes. Medicines, cancer treatment, immune treatment, physiologic stress, exercise, and many illnesses can change one or more component counts.
No. NLR divides neutrophils by lymphocytes, PLR divides platelets by lymphocytes, and SII multiplies platelets by neutrophils before dividing by lymphocytes.
No. It does not order repeat blood counts, cultures, imaging, referral, medication, dose, admission, cancer therapy, transfusion, or another treatment.
Related Calculators
NLR
Calculate NLR from matched absolute counts or percentages with exact decimal arithmetic and neutral interpretation limits.
PLR
Calculate platelet-to-lymphocyte ratio from matched absolute blood counts with exact unit normalization and nonspecific interpretation limits.
ANC
Calculate ANC from same-CBC WBC, segmented neutrophils, and separately reported bands with explicit units and neutral limits.
Disclaimer
Educational and informational reference only. Not intended to replace professional medical advice, diagnosis, treatment, or independent verification.