Skip to main content
Calcimator

Anticoagulation Calculator

Warfarin dose adjustment calculator based on current INR, target range, and weekly dose with recheck interval recommendations.

Inputs

mg

Results

Dose Adjustment

0%

New Weekly Dose

35 mg

New Average Daily Dose5 mg
Recheck INR In28 days
Current Status1
Bleeding Risk Level0
How to Use This Calculator
  1. Enter the patient's most recent INR result.
  2. Set the target INR range (low and high bounds) for the indication.
  3. Enter the current weekly warfarin dose in mg.
  4. Review Dose Adjustment (%), New Weekly Dose (mg), and Recheck INR In (days).
  5. For clinical use — always apply clinical judgment; this tool supports but does not replace provider decisions.

What each input means

Current INR
Most recent INR lab result.
Target INR (low)
Lower bound of target INR range. Typically 2.0 for AFib/DVT, 2.5 for mechanical valves.
Target INR (high)
Upper bound of target INR range. Typically 3.0 for AFib/DVT, 3.5 for mechanical valves.
Current weekly dose
Total warfarin dose per week (sum of all daily doses).

What each result means

Dose Adjustment
Suggested % change in weekly dose. -100% means hold warfarin.
New Weekly Dose
Suggested new total weekly warfarin dose.
New Average Daily Dose
New weekly dose divided by 7.
Recheck INR In
Recommended days until next INR check.
Current Status
0 = Sub-therapeutic, 1 = Therapeutic, 2 = Supra-therapeutic.
Bleeding Risk Level
0 = Low (INR ≤3), 1 = Moderate (3-4), 2 = High (4-5), 3 = Critical (>5).

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Current INR = 2.5, Target INR (low) = 2, Target INR (high) = 3, Current weekly dose = 35 = 4 input(s) provided
  2. Calculate Dose Adjustment
    Dose Adjustment
    0 = 0
  3. Calculate New Weekly Dose
    35 = 35
  4. Calculate New Average Daily Dose
    New Average Daily Dose = newWeeklyDose / 7
    5 = 5
  5. Calculate Recheck INR In
    Recheck INR In
    28 = 28

Related Calculators

The questions that sit next to this one — chosen by subject, including calculators filed under a different category.

Cardiology

EKG Interval Calculator

Analyze ECG/EKG intervals with corrected QT calculation (Bazett, Fridericia, Hodges) and interpretation of PR, QRS, and QT intervals.

Cardiology

Cardiac Risk Calculator

Revised Cardiac Risk Index (RCRI/Lee Index) for estimating perioperative major cardiac event risk.

Cardiology

Pacemaker Programming Calculator

Calculate pacemaker timing intervals, battery drain, TARP, tracking limits, and safety margins from programmed settings.

Pharmacy

Warfarin Dose Adjustment Calculator

Estimate warfarin dose adjustments based on current INR values using proportional adjustment guidelines.

More in Medical & Clinical.