What anticoagulants does this calculator cover?

The calculator covers three common parenteral anticoagulants: unfractionated heparin (UFH), low-molecular-weight heparin enoxaparin (brand name Lovenox), and fondaparinux (Arixtra). Oral anticoagulants such as warfarin (which requires individualized titration based on INR lab monitoring) and DOACs like apixaban or rivaroxaban (which use standard flat dosing with clinical dose-reduction criteria) are not included because they do not rely on direct weight-based calculation nomograms.

How is the heparin infusion rate calculated?

For therapeutic heparin, the standard weight-based protocol uses an IV bolus of 80 units/kg (max 10,000 units) followed by a continuous infusion starting at 18 units/kg/hr (max 2,500 units/hr). The infusion is then titrated based on aPTT results per institutional nomogram. This calculator provides the initial starting doses only.

Does enoxaparin dose change in obesity or renal failure?

Yes. For morbid obesity (BMI >40 or weight >150 kg), some guidelines recommend capping enoxaparin at 150–180 mg/dose or using anti-Xa monitoring rather than full weight-based dosing. For CrCl <30 mL/min, the therapeutic enoxaparin dose is reduced to 1 mg/kg once daily. This tool displays the standard weight-based dose; renal or obesity adjustments must be applied separately by the clinician.

What is bridging anticoagulation?

Bridging refers to short-term use of a fast-acting anticoagulant (typically LMWH) around a procedure or surgery when the patient's oral anticoagulant (e.g., warfarin) must be interrupted. Bridging doses are typically therapeutic-intensity LMWH given twice daily, started 2–3 days before the procedure and resumed after.

Is this tool suitable for pediatric patients?

No. Pediatric anticoagulant dosing differs substantially from adult dosing — especially for heparin. This tool uses adult weight-based protocols. For pediatric dosing, consult a pediatric clinical pharmacist or age-specific references.

Can I use this to make clinical decisions?

This tool is for educational and reference purposes only. Anticoagulant dosing must account for renal function, bleeding risk, body composition, indication, and real-time lab monitoring (aPTT, anti-Xa levels). Always verify doses with current institutional protocols and a licensed prescriber before administering any anticoagulant.

Anticoagulant Dose Calculator

Enter patient weight and select an anticoagulant and indication to calculate weight-based dosing for heparin (UFH), enoxaparin (LMWH), or fondaparinux.

Patient & Drug Selection

Patient Weight

Anticoagulant

Indication

For educational reference only. Always verify with institutional protocols and a licensed prescriber before clinical use.

Enter weight, select a drug and indication, then click Calculate.

Quick Reference — All Indications

Indication	Dose	Route / Freq

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Summary

This calculator provides weight-based dosing references for three common anticoagulants: unfractionated heparin (UFH), enoxaparin (LMWH), and fondaparinux. Indications covered include VTE treatment (therapeutic), VTE prophylaxis, acute coronary syndrome (ACS), and bridging anticoagulation. Doses are derived from widely referenced clinical guidelines (ACC/AHA, ACCP). This tool is for educational reference only — always verify with institutional protocols and a licensed prescriber before administering any anticoagulant.

How it works

Enter the patient weight in kilograms or pounds (auto-converted).
Select the anticoagulant: Heparin UFH, Enoxaparin, or Fondaparinux.
Choose the clinical indication (e.g., VTE treatment, prophylaxis, ACS, bridging).
The calculator applies standard weight-based dosing formulas from clinical guidelines.
Results display the calculated dose(s), dosing frequency, and any weight-based caps.
A disclaimer reminds users to confirm with institutional protocols before clinical use.

Use cases

Calculate enoxaparin dose for a patient with deep vein thrombosis (DVT).
Determine heparin bolus and infusion rate for VTE treatment by weight.
Look up fondaparinux prophylactic dose for a post-operative patient.
Reference baseline weight-based enoxaparin dose before applying clinical renal or obesity adjustments.
Reference bridging anticoagulation doses during perioperative management.
Support pharmacology education and clinical training scenarios.
Cross-check a written order against standard weight-based dosing tables.
Calculate ACS heparin dosing for unstable angina or NSTEMI management.

Frequently Asked Questions

Last updated: 2026-06-15 · Reviewed by Nham Vu