Trophic Level Energy Transfer Calculator (10% Rule)

How it works

energy at level n = NPP × efficiencyⁿ⁻¹ · producer energy to support a consumer = its need ÷ efficiency^(level − 1) · area = that energy ÷ NPP per m² · Lindeman efficiency ≈ 10% (range 5–20%)

Every time energy passes from one organism to the one that eats it, most is lost — spent on the eaten organism's own metabolism, left uneaten, or excreted — and Raymond Lindeman's classic measurement put the average at about a tenth transferred. Compounding that loss over successive levels produces the energy pyramid: a hundredth of the plant energy reaches a carnivore, a thousandth an animal that eats carnivores, which is why big predators need vast territories and why chains peter out after four or five links regardless of how productive the base is. The same arithmetic explains the land cost of animal foods and the choice of which fish are cheap to farm: the lower the trophic level, the more food per hectare.

Worked example

On cropland fixing 10,000 kcal/m²/yr with 10% transfer, herbivores get 1,000, carnivores 100 and level-4 predators 10 kcal/m²/yr — too little to sustain a population, so the chain ends there. A wolf-sized carnivore needing 1,000,000 kcal/yr at level 3 draws on 100,000,000 kcal of plant production, about 1 ha of cropland or 2–5 ha of grassland in this idealised model (real wolves range over far more, because they harvest only a small fraction of the herbivores); feeding a person on beef takes roughly 10 times the land of feeding them on grain.

Frequently asked questions