How to Use This Calculator
Pick the animal species, enter the dose used in the study in mg/kg and a human reference weight in kg. Click Convert to HED to see the human equivalent dose in mg/kg and in mcg/kg, and the total in mcg at that reference weight.
Why Surface Area, Not Just Body Weight
A simple mg-per-kg conversion overstates the human-equivalent dose because smaller animals have a higher metabolic rate relative to their size. The Km factor corrects for this by scaling on body surface area instead of raw body weight, which is why a mouse dose of 10 mg/kg does not translate to 10 mg/kg in a human, it translates to roughly 0.8 mg/kg once the surface-area correction is applied. Getting this conversion right matters most when working from a published animal study and trying to understand what dose range the study actually corresponds to in human terms.
Where This Fits Alongside Other Research Tools
To compare an HED with lab figures, the Peptide Dosage Calculator converts a mcg/kg figure into a syringe reading at a given concentration, and the BAC Water Calculator works out that concentration from the vial size and the water added.
A Note on Interspecies Extrapolation
Allometric scaling is a standard pharmacological estimation method, not a guarantee that human and animal responses will match. Absorption, metabolism, and receptor sensitivity can all differ between species in ways a surface-area formula does not capture. Treat a scaled dose as a starting reference point for further reading, not a finished number.
Who Should Use This
Researchers reading preclinical papers who want to compare animal study doses with human-scale amounts.
What This Calculator Does
The Allometric Dose Scaling Calculator converts an animal study dose in mg/kg into a human equivalent dose (HED) with the FDA body-surface-area (Km) method.
Formula Used
HED (mg/kg) = Animal dose (mg/kg) × (Animal Km ÷ 37), where human Km = 37 and, for example, mouse = 3, rat = 6, dog = 20. Total (mcg) = HED (mcg/kg) × Human reference weight (kg)Example Calculation
Limitations
The Km method is a rough approximation. It does not account for differences in bioavailability, receptor density, protein binding or route of administration between species, and an HED is a starting point for research discussion, not a dose to administer.
Frequently Asked Questions
How do I convert a mouse dose to a human equivalent dose?
Multiply the mouse dose in mg/kg by 3, the mouse Km factor, then divide by 37, the human Km factor. For example, a mouse dose of 10 mg/kg gives 10 × 3 ÷ 37 = 0.81 mg/kg.
What is an allometric scaling calculator?
An allometric scaling calculator converts a dose between species using body surface area, through the Km factor, instead of body weight alone. This one converts an animal study dose in mg/kg to a human equivalent dose using the FDA Km method.