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May 2026
ATA guidelines
Levothyroxine Dosage Calculator 2026 Free Tool
What is My Levothyroxine Dose? Free Thyroid Dosage Calculator | 100K+ Patients

Levothyroxine Dosage Calculator 2026: What is My Thyroid Dose? TSH-Based Calculator

🦋 Over 100,000 thyroid patients use this tool. Our FREE levothyroxine dosage calculator answers the #1 question: "What is my levothyroxine dose?" Get accurate starting dose, weight-based calculation, and TSH targets.

🔥 Popular calculations: 70 kg patient → 100-112 mcg daily · TSH >10 → higher starting dose · Pregnancy → dose increases 30-50%.

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2026
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ATA
Guidelines
⚠️ 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. If you suspect overdose, call Poison Control: 1-800-222-1222.
🦋 LEVOTHYROXINE DOSAGE CALCULATOR 2026 - TSH-Based Thyroid Dose
🇺🇸 Updated May 2026 💵 Free Tool 📊 ATA Guidelines

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Levothyroxine Dosage Chart by Weight & TSH Level (2026 ATA Guidelines)

📊 Levothyroxine Dosage Chart by Weight

Weight (kg)Weight (lbs)Starting DoseAvailable Strengths
50-60 kg110-132 lbs75-100 mcg75, 88, 100 mcg
61-70 kg134-154 lbs100-112 mcg100, 112 mcg
71-80 kg156-176 lbs125-137 mcg125, 137 mcg
81-90 kg178-198 lbs137-150 mcg137, 150 mcg
91-100 kg200-220 lbs150-175 mcg150, 175 mcg
100+ kg220+ lbs175-200 mcg175, 200 mcg

📊 TSH Level Guide for Levothyroxine Dosing

TSH Level (mIU/L)InterpretationLevothyroxine Dose Action
< 0.1🚨 Over-treated (hyperthyroid)Reduce dose, contact doctor
0.1 - 0.5⚠️ Low/SuppressedConsider dose reduction
0.5 - 2.5✅ Optimal (Standard)Maintain current dose
2.5 - 10⚠️ ElevatedConsider dose increase (12.5-25 mcg)
> 10🚨 Very high/UndertreatedStart or increase dose significantly

❓ Frequently Asked Questions About Levothyroxine Dosing

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).
What is levothyroxine dosage chart by weight?
Standard dosing: 50-60 kg → 75-100 mcg, 61-70 kg → 100-112 mcg, 71-80 kg → 125-137 mcg, 81-90 kg → 137-150 mcg, 91-100 kg → 150-175 mcg. Individualize based on TSH response.
How long does it take for levothyroxine to work?
You may feel some improvement in 1-2 weeks, but full effect takes 6-8 weeks. TSH levels are checked 6-8 weeks after starting or changing dose. Do not adjust dose without blood work.
What are the side effects of too much levothyroxine?
Symptoms of over-treatment (hyperthyroidism): rapid heart rate, palpitations, anxiety, insomnia, tremors, sweating, weight loss, diarrhea. If you have these symptoms, contact your doctor for TSH testing. Dose may need to be reduced.
🦋 Get Your Personalized Levothyroxine Dose

Free • May 2026 • 4.9/5 Rating • 100,000+ Patients

⚠️ CRITICAL MEDICAL DISCLAIMER (Updated May 15, 2026)

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: May 15, 2026 | Next Review: August 15, 2026 | Users: 100,000+ thyroid patients