Because of the growing human population, increasing agricultural yields is becoming increasingly more important. However, various environmental crises have led society to demand a reduction in the environmental damage caused by agriculture. Until now, the economic and ecological aspects of plant cultivation have developed largely independently. Here, we propose a novel ecological intensification index (EII) that integrates both economic and ecological goals, measured in relative units as the realized proportion of a possible maximum value. The EII can incorporate multiple ecological and/or economic measures with different weights to balance societal needs, environmental concerns, and scientific knowledge. Using the EII will provide a quantitative target for breeders, agronomists, and farmers to catalyze innovation toward a minimal ecological impact of agriculture.