Measuring Sustainable Development:

Sustainable human development will occur when all humans can have fulfilling lives without degrading the planet. This, we believe, is the ultimate goal. Two leading indicators have identified how we can get there. Ecological Footprint data tells us that, given current population and available land area, an Ecological Footprint of less than 1.7 global hectares per person makes a country’s resource demands globally replicable.

The United Nations’ Human Development Index (HDI)—which measures a country’s average achievements in the areas of health, knowledge, and standard of living—tells us that an HDI higher than 0.8 is considered "high human development."

Combining these two indicators gives clear minimum conditions for sustainable human development and shows how much more we need to "think inside the box."