Allometric Scaling Calculator
Convert rodent study doses to human equivalent doses (HED) using FDA 2005 allometric scaling guidance. Based on body surface area (BSA) Km factors from the FDA's “Estimating the Maximum Safe Starting Dose in Initial Clinical Trials for Therapeutics in Adult Healthy Volunteers” guidance document.
Formula (FDA 2005 Guidance)
Km is a body surface area normalization factor (body weight in kg ÷ BSA in m²). Dividing by a larger human Km (37) typically yields a lower HED than the animal dose — reflecting the fact that smaller animals have proportionally larger surface areas and faster metabolism.
Animal Study Parameters
Typical: 20 g
FDA guidance uses 60 kg reference human
Quick Presets
Km Factors Used
Animal Dose Summary
Human Equivalent Dose (HED)
Species Km Reference Table
Kmvalues from FDA Guidance (2005) — used in HED conversion
| Species | Km | Avg Weight | HED Factor vs Human | Typical Route |
|---|---|---|---|---|
| Mouse | 3 | 20 g | 0.081× | IP, SC, IV |
| Rat | 6 | 150 g | 0.162× | IP, SC, IV, PO |
| Hamster | 5 | 60 g | 0.135× | IP, SC |
| Guinea Pig | 8 | 400 g | 0.216× | SC, IP |
| Rabbit | 12 | 1.8 kg | 0.324× | SC, IV, PO |
| Cat | 16 | 3 kg | 0.432× | SC, IM, IV |
| Monkey (NHP) | 12 | 3 kg | 0.324× | SC, IV, IM |
| Dog | 20 | 10 kg | 0.541× | SC, IV, PO |
| Human (reference) | 37 | 60 kg | 1.000× | SC, IV, PO, IN |
Cross-Species HED Comparison
What the same animal dose (10 mcg/kg) maps to across all species → 60 kg human HED
| If Studied In | Km | HED (mg/kg) | Absolute HED (60 kg) |
|---|---|---|---|
| Mouse← selected | 3 | 0.811 mcg/kg | 48.65 mcg |
| Rat | 6 | 1.62 mcg/kg | 97.30 mcg |
| Hamster | 5 | 1.35 mcg/kg | 81.08 mcg |
| Guinea Pig | 8 | 2.16 mcg/kg | 129.7 mcg |
| Rabbit | 12 | 3.24 mcg/kg | 194.6 mcg |
| Cat | 16 | 4.32 mcg/kg | 259.5 mcg |
| Monkey (NHP) | 12 | 3.24 mcg/kg | 194.6 mcg |
| Dog | 20 | 5.41 mcg/kg | 324.3 mcg |
⚠ Important Limitations
What allometric scaling DOES account for:
- • Metabolic rate differences between species
- • Body surface area normalization
- • Pharmacokinetic equivalence (first approximation)
- • FDA-validated scaling methodology
What allometric scaling DOES NOT account for:
- • Species-specific receptor density/affinity differences
- • Route-specific bioavailability differences
- • First-pass metabolism variation by species
- • Protein binding differences
- • Target organ differences or disease state
- • Intranasal CNS transport (route-specific)
Research Use Only — Not for Clinical Use
HED calculations are provided for research modeling and study design purposes only. This calculator does not constitute medical advice, clinical translation guidance, or dosing recommendations. All Nexphoria peptides are for in vitro and preclinical research only and are not approved for human administration.