Rat to Human Dose (HED) Calculator
Calculation Results:
Human Equivalent Dose (HED): mg/kg
Total Human Dose: mg
Understanding Rat to Human Dose Conversion
Converting pharmacological doses from animal models to humans is a critical step in clinical research and drug development. This process is known as determining the Human Equivalent Dose (HED). Simply adjusting by body weight (mg/kg) is often inaccurate because metabolic rates and physiological processes vary significantly between species.
The Allometric Scaling Formula
The standard FDA guidance for converting animal doses to HED uses Body Surface Area (BSA) normalization. BSA correlates better across species for several biological parameters, including basal metabolic rate and blood volume. The conversion utilizes "Km factors," which represent the ratio of body weight to body surface area.
HED (mg/kg) = Animal Dose (mg/kg) × (Animal Km / Human Km)
- • Rat Km Factor: 6
- • Human (Adult) Km Factor: 37
- • Conversion Factor (Rat to Human): 0.162
Example Calculation
If a study finds that a dose of 50 mg/kg is effective in rats, the calculation for a human equivalent would be:
50 mg/kg × (6 / 37) = 8.11 mg/kg in humans.
For a 60 kg adult, the total starting dose would be 8.11 × 60 = 486.6 mg.
Important Safety Disclaimer
This calculator is for educational and informational purposes only. Interspecies scaling is complex and must account for pharmacokinetics, bioavailability, and toxicity profiles. Never use results from this tool to determine dosages for human consumption or clinical trials without professional medical and scientific supervision.