Absolute Neutrophil Count (ANC) Calculator
Calculate ANC from WBC and differential to classify neutropenia severity and assess infection risk.
Inputs
Formula: ANC = WBC × (% Neutrophils + % Bands) / 100 × 1000
Disclaimer: For educational purposes only. Not a substitute for clinical judgment.
About This Tool
What Is the Absolute Neutrophil Count?
The absolute neutrophil count (ANC) is a calculated value that represents the total number of neutrophils (both mature segmented neutrophils and immature bands) in the peripheral blood. It is calculated by multiplying the total white blood cell count (WBC) by the combined percentage of neutrophils and bands, then dividing by 100. The ANC is the primary measure used to define neutropenia and assess a patient's risk for bacterial and fungal infections, particularly in the context of cancer chemotherapy.
Neutropenia Classification and Risk
Neutropenia is classified by severity: mild (ANC 1,000–1,499/μL), moderate (ANC 500–999/μL), and severe (ANC <500/μL). Infection risk increases significantly below an ANC of 500/μL and becomes extremely high below 100/μL (profound neutropenia). The duration of neutropenia is also critical — patients with expected neutropenia lasting >7 days are at considerably higher risk than those with brief neutropenic episodes. The MASCC score and CISNE index can further risk-stratify febrile neutropenic patients.
Febrile Neutropenia Management
Febrile neutropenia (defined as ANC <500/μL or expected to decrease to <500/μL, with a single temperature ≥38.3°C or sustained ≥38.0°C over one hour) is a medical emergency. Management includes immediate blood cultures (at least 2 sets, including from any central line), empiric broad-spectrum antibiotic therapy (typically an antipseudomonal beta-lactam such as cefepime, meropenem, or piperacillin-tazobactam), and assessment for hemodynamic instability. Low-risk patients (MASCC ≥21) may be candidates for oral fluoroquinolone + amoxicillin-clavulanate as outpatient therapy.
Drug-Induced Neutropenia
Beyond chemotherapy, many drugs can cause neutropenia. Notable examples include clozapine (requires mandatory ANC monitoring), methimazole/PTU, carbamazepine, trimethoprim-sulfamethoxazole, and various antibiotics. Drug-induced agranulocytosis typically resolves within 1–3 weeks of drug discontinuation. G-CSF may be used to hasten recovery in severe cases.
🔑 Clinical Pearls
- Always include bands in the ANC calculation when reported — some labs report only the absolute neutrophil value directly.
- In the absence of a manual differential, the automated neutrophil count is acceptable for ANC calculation.
- ANC nadir typically occurs 7–14 days after chemotherapy — timing varies by regimen and agent.
- Ethnic neutropenia (benign ethnic neutropenia) is common in individuals of African descent — baseline ANC 1,000–1,500 may be normal and does not confer the same infection risk as chemotherapy-induced neutropenia.
- In febrile neutropenia, do not delay antibiotics for imaging or other workup — "door to antibiotic" time matters.
Key References
- Freifeld AG, et al. Clinical practice guideline for the use of antimicrobial agents in neutropenic patients with cancer. Clin Infect Dis. 2011;52(4):e56-e93.
- Klastersky J, et al. The Multinational Association for Supportive Care in Cancer risk index. J Clin Oncol. 2000;18(16):3038-3051.
- Crawford J, et al. NCCN Clinical Practice Guidelines: Myeloid Growth Factors. 2024.
- Andersohn F, Konzen C, Garbe E. Systematic review: agranulocytosis induced by nonchemotherapy drugs. Ann Intern Med. 2007;146(9):657-665.
Formula last verified: February 2026