Heparin Infusion Calculator

The Heparin Infusion Calculator estimates the initial intravenous unfractionated heparin bolus dose and continuous infusion rate based on body weight and selected protocol intensity. This tool helps healthcare professionals determine appropriate anticoagulation dosing for conditions like venous thromboembolism or atrial fibrillation. Whether you are adjusting for standard therapeutic levels or high-intensity needs, this calculator supports precision by applying maximum dose caps to patient safety protocols.

Actual body weight (Range: 30 - 200 kg)
Select the institutional anticoagulation protocol.
Upper limit for the initial bolus dose.
Upper limit for the continuous infusion rate.

How Heparin Dosing Is Calculated

The calculation uses a standard weight-based nomogram recommended by the American College of Chest Physicians (ACCP). First, the raw dose is found by multiplying the patient's weight in kilograms by a protocol-specific factor (e.g., 80 units/kg for a standard bolus). Second, the calculator compares this raw number against the institution-defined maximum cap. The final displayed dose is the lower of the two numbers, ensuring the dose never exceeds safety limits regardless of patient size.

Final Dose = min( (Weight × Factor), Maximum Cap )

Where:

  • Weight = Patient body weight in kg
  • Factor = Protocol units per kg (e.g., 80 U/kg for bolus)
  • Maximum Cap = Institution-defined safety limit

What Your Calculation Mean

For Standard Therapeutic Goals: A result of approximately 80 units/kg bolus and 18 units/kg/hr infusion is intended for patients with acute venous thromboembolism (VTE) requiring rapid anticoagulation.

For High-Intensity Needs: Results around 100 units/kg are typically used for procedures like cardiopulmonary bypass or acute coronary syndromes where higher clot prevention is critical.

For Bleeding Risk: If the result uses a low-intensity factor (e.g., 60 units/kg), it indicates a conservative approach for patients with recent surgery or high bleeding risk.

Important Note

This calculator provides the initial loading dose only. Subsequent dosing adjustments must be based on aPTT (activated Partial Thromboplastin Time) blood test results per your hospital's nomogram.

Calculation logic verified using publicly available standards.

View our Accuracy & Reliability Framework →