The growth of carnivorous plants is usually limited or co-limited by shortage of available mineral nutrients N, P, and K in barren soils or waters. Carnivorous plants capture animal prey, absorb mineral nutrients from digested prey, and partly overcome the nutrient limitation. Therefore, prey capture leads invariably to marked and significant growth increase as the main ecophysiological benefit of carnivory. Here, a novel functional-ecological approach of how to quantify growth benefit efficiency of carnivory is explained. It expresses plant growth increase due to prey catching or feeding per amount of N or P or K theoretically absorbed from prey (or applied in mineral solution onto the traps) in growth experiments.