Levothyroxine Dosage Calculator

Your details

Your current body weight. For patients with obesity, ideal body weight is used automatically.
kg
Height is used to calculate ideal body weight (Devine formula) when BMI is above 30.
cm
The Devine ideal body weight formula differs by sex (45.5 vs 50 kg base at 5 ft).
Patients aged 65 or older typically start at a lower dose (25-50 mcg/day) to avoid cardiac strain.
years
The clinical scenario sets the base dose-per-kg multiplier. Cancer patients need higher doses to suppress TSH; subclinical patients need less.
Ischemic heart disease, arrhythmia, or heart failure. Caps the starting dose at 12.5-25 mcg/day regardless of weight to prevent angina or arrhythmia.
Calculated starting doseModerate-high dose
112mcg/day

Weight-based dose before rounding to a commercial tablet

Nearest tablet strength112mcg
Effective weight used70kg
BMI24.2kg/m2
Target TSH range0.5 to 2.5 mIU/L
Two-tablet alternative25 mcg + 88 mcg
Ideal body weight61.4kg
112 mcg/day
Low start<25Standard25-100Moderate-high100-150High dose150+

Starting dose estimate: 112 mcg/day for new hypothyroidism.

  • Your calculated starting dose is 112.0 mcg/day, rounded to 112 mcg - the nearest commercially available tablet.
  • Target TSH for new hypothyroidism: 0.5 to 2.5 mIU/L.

Next stepRecheck TSH 6-8 weeks after starting or changing your dose. Bring this result to your clinician - they will determine your actual prescription.

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