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Weight-Based Heparin Drip Calculator

Estimate bolus and maintenance heparin infusion rates using common weight-based nomograms. Always follow your institution’s anticoagulation protocol.

⚠️ Safety note: High-risk: heparin requires protocol-specific nomograms, aPTT/anti-Xa monitoring, and pharmacy or prescriber verification.

Understanding this tool

Why nurses use it

Weight-based heparin nomograms are common for VTE and ACS pathways. Nurses use bolus and maintenance unit calculations as a starting point before applying the institution-specific protocol and aPTT/anti-Xa monitoring.

When to use it

Use only as an illustrative check alongside your approved heparin protocol — never as the sole basis for prescribing or titrating heparin.

Calculate

Converted to kg for calculation.

How to use this calculator

  1. Confirm patient weight.
  2. Select your unit’s nomogram style or enter custom units/kg/hr if directed.
  3. Compare output with the protocol chart and pharmacy.
  4. Monitor aPTT or anti-Xa per policy.

How the calculation works

Common teaching example: bolus 80 units/kg and maintenance 18 units/kg/hr. Actual protocols vary — always use the mandated nomogram.

Protocol-specific (e.g. 80 U/kg bolus + 18 U/kg/hr maintenance)

Formula used by this tool — verify units before applying at the bedside.

Worked example

80 kg on standard protocol: bolus ≈ 6400 U; maintenance ≈ 1440 units/hr — always follow local nomogram.

Limitations & clinical notes

  • Institution protocols vary — never use generic nomograms without local approval.
  • Requires aPTT or anti-Xa monitoring per protocol.

References

Key sources: ASH — Antithrombotic therapy guidelines.

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Disclaimer: This calculator is for educational and bedside double-check purposes only. It does not replace institutional protocols, prescriber orders, pharmacist verification, or clinical judgment. Always follow your local policies — especially for high-risk medications, infusions, pediatrics, and critical care. If the patient is acutely unwell, escalate immediately rather than relying on any calculator output.