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Free warfarin (Coumadin) dose adjustment calculator from measured INR and goal range. Converts your current schedule into total weekly milligrams, suggests a percentage change for educational comparison, and flags when self-titration is inappropriate. Always follow your anticoagulation clinic or prescriber.
Last updated: April 13, 2026
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How do you track dose?
INR 3.1–3.4
INR modestly above target
Some clinics reduce total weekly dose slightly (~5–10%) or omit one dose when INR is just above goal. Exact steps vary by center and bleeding risk.
Equivalent weekly total: 35.0 mg/week
Suggested change to weekly total: -7.5%
Rounded suggested weekly total: 32.5 mg/week
≈ average daily if split evenly: 4.64 mg/day
Recheck INR in 2–7 days after adjustment.
Not medical advice
Warfarin dosing must follow your anticoagulation clinic or prescriber. Tablet strengths vary (1, 2, 2.5, 3, 4, 5, 6, 7.5, 10 mg). This tool does not replace protocols for bridging, procedures, pregnancy, or liver failure.
Separate logic for INR 2.0–3.0 vs tighter 2.5–3.5 goals so supersubtherapeutic and supratherapeutic bands align with how many clinics teach titration.
Enter either total weekly milligrams or an average daily dose; the tool annualizes to weekly before applying a percent adjustment.
Above roughly INR 5, the calculator stops suggesting home percentage math and directs users to professional management pathways.
Shows a rounded suggested weekly total and an even-split daily average for discussion—not a tablet schedule (you still map mg to tablet strengths with your pharmacist or clinic).
Each band includes generic recheck timing language typical of outpatient anticoagulation education.
Warfarin sodium is the generic name; Coumadin was a common brand. INR monitoring principles are the same for any VKA managed this way.
INR 3.2, target 2–3, current total 35 mg/week (~5 mg/day average).
INR 3.1–3.4
INR modestly above target
Suggested weekly change: -7.5% → about 32.5 mg/week
Warfarin blocks vitamin K–dependent clotting factors; the INR summarizes the extrinsic pathway. Because onset and offset are slow, dose changes are small and spaced apart. Most outpatient programs teach percent changes on the total weekly milligram burden rather than on individual tablet colors, then translate the new weekly total into a practical tablet plan.
See also CHA2DS2-VASc and creatinine clearance for related clinical context.
Get Custom Calculator for Your PlatformThe tool places INR in the “slightly below target” band and suggests roughly a +7.5% increase in weekly total → about 45 mg/week before rounding to feasible tablets. Your clinic might choose a different increment or order an earlier repeat INR.
Share with others on warfarin—remind them to follow their clinic.
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