v1.0.0

HED Engine

Convert animal doses (mg/kg) to human equivalent dose using body-surface-area (Km) scaling.

Conversion mode

Choose what you’re converting.

Species

Ref wt: 0.15 kg · Km: 6

Animal dose (mg/kg)

Human Km assumed: 37 (60 kg adult)

Human weight (kg)

Used to compute mg/day.

Display decimals

Formatting only (no effect on math).

Formula (Km method):
HED (mg/kg) = Animal dose (mg/kg) × (Km_animal / Km_human) and mg/m² = Km × mg/kg.

Show Km reference table (quick view) — values assume 60 kg adult human

Species	Km	Divide by	Multiply by	Ref wt (kg)	Range (kg)
Mouse	3	12.33	0.081	0.02	0.011–0.034
Hamster	5	7.4	0.135	0.08	0.047–0.157
Rat	6	6.17	0.162	0.15	0.08–0.27
Ferret	7	5.29	0.189	0.3	0.16–0.54
Guinea pig	8	4.63	0.216	0.4	0.208–0.700
Rabbit	12	3.08	0.324	1.8	0.9–3.0
Dog	20	1.85	0.541	10	5–17
Monkeys (rhesus)	12	3.08	0.324	3	1.4–4.9
Marmoset	6	6.17	0.162	0.35	0.14–0.72
Squirrel monkey	7	5.29	0.189	0.6	0.29–0.97
Baboon	20	1.85	0.541	12	7–23
Micro pig	27	1.37	0.73	20	10–33
Mini pig	35	1.06	0.946	40	25–64

These factors are widely reproduced from FDA starting-dose guidance and the Nair 2016 review.

Human equivalent dose (HED)

HED (mg/kg)

—

Total (mg/day)

—

Human wt (kg)

Factor: multiply by 0.162162 or divide by 6.167.

MRSD (Start Dose)

Factor

— mg/kg

Total: — mg/day

Maximum Recommended Starting Dose calculated using a safety factor of 10 (MRSD = HED / 10).

This is a body-surface-area (Km) scaling tool for dose translation (common in preclinical → first-in-human planning).
Km factors can vary with actual animal weight; use Custom weights when you have true study weights.
Scaling by mg/m² is generally not used for some routes (e.g., topical, nasal, IM/SC) and certain large proteins—consider PK/PD and guidance context.
Actual FIH starting dose selection may be driven by MABEL, PK/PD modeling, or target-mediated toxicity rather than MRSD, especially for biologics or first-in-class compounds.
This is a learning tool and does not replace regulatory guidance or professional judgment.