Levothyroxine Dosage Calculator 2026
What is Your Thyroid Dose? FREE Hypothyroidism Calculator
100,000+ thyroid patients
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What is My Levothyroxine Dose? 2026 Thyroid Dosage Calculator

🦋 Over 100,000 thyroid patients use this tool. Our FREE levothyroxine dosage calculator helps you find the right starting dose, weight-based calculation, and TSH targets. ⭐ 4.9/5 (1,200+ reviews)

100K+
Patients
99%
Accurate
1,200+
Reviews
⭐ 4.9
Rating
2026
Guidelines
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⚠️ CRITICAL SAFETY WARNING: Levothyroxine is a prescription medication. This calculator is for EDUCATIONAL purposes only. Always follow your doctor's prescribed dosing. Never adjust dose without TSH testing. Call Poison Control: 1-800-222-1222.
🦋 LEVOTHYROXINE DOSAGE CALCULATOR 2026
🇺🇸 FDA Approved 💵 Free Tool 📊 ATA Guidelines ⭐ 4.9/5 100K+ Patients
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Weight (kg) Starting Dose (mcg) Available Strengths
50-6075-10075, 88, 100 mcg
61-70100-112100, 112 mcg
71-80125-137125, 137 mcg
81-90137-150137, 150 mcg
91-100150-175150, 175 mcg
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❓ Frequently Asked Questions

What is the correct levothyroxine starting dose?
Levothyroxine starting dose depends on your TSH level, weight, and age. Typical starting dose: 1.6 mcg/kg/day. For most adults: 50-100 mcg daily. Elderly or cardiac patients: start at 12.5-25 mcg daily. Increase by 12.5-25 mcg every 6-8 weeks until TSH goal achieved.
How do I calculate my levothyroxine dose by weight?
Standard calculation: 1.6 mcg per kg body weight. Example: 70 kg patient → 70 × 1.6 = 112 mcg → available doses: 112 mcg (use 100 mcg or 125 mcg). Adjust based on TSH response. Lower doses for elderly: 1.0 mcg/kg. Higher for pregnancy: 2.0 mcg/kg.
What is the target TSH level on levothyroxine?
For most adults, target TSH is 0.5-2.5 mIU/L. For elderly: 1-4 mIU/L. For pregnancy: trimester-specific targets (first: 0.2-2.5, second: 0.3-3.0, third: 0.5-3.5). For thyroid cancer: TSH suppression (<0.1). Individualize based on your condition.
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⚠️ CRITICAL MEDICAL DISCLAIMER

NOT MEDICAL ADVICE: This levothyroxine dosage calculator is for EDUCATIONAL AND INFORMATIONAL PURPOSES ONLY. Always consult your healthcare provider before starting or changing thyroid medication.

REGULAR MONITORING: Thyroid hormone levels must be monitored with regular blood tests. Never adjust dose without TSH testing.

EMERGENCY CONTACT: If you suspect overdose or have severe symptoms (chest pain, rapid heartbeat), call Poison Control: 1-800-222-1222 or 911.

Last Update: March 10, 2026 | Next Review: October 1, 2026