Sustainability Score Calculator

Your carbon footprint is the sum of greenhouse gas emissions, measured in CO2 equivalent tonnes, directly or indirectly caused by your activities over a year. The global average is around 4 tonnes of CO2 per person per year; in the US it runs closer to 14-16 tonnes.

Diet is one of the biggest levers. Beef alone produces roughly 60 kg of CO2 equivalent per kilogram of food, compared to 2-3 kg for chicken and under 1 kg for legumes. Switching from a heavy meat diet to a plant-based one cuts diet-related emissions by roughly 75%.

Transportation’s share depends heavily on flight frequency. A single round-trip transatlantic flight can add 1.5-3 tonnes to your footprint. Daily driving in a gasoline car contributes 2-4 tonnes annually depending on distance. Electric vehicles cut this by 50-70% on average US grid electricity, more so on renewable power.

Home energy use, meaning heating, cooling and appliances, accounts for roughly 20-30% of household emissions. Switching to renewable electricity eliminates most of this. Upgrading to a heat pump from gas heat cuts heating emissions by 60-70%.

Consumer goods and services typically add 2-4 tonnes annually for an average American. New electronics, fast fashion, and frequent purchases all have embedded carbon from manufacturing and shipping.

This calculator produces a rough estimate using published emission factors. Your actual footprint depends on specifics (what grid your electricity comes from, how far you drive, what you buy) that a full lifecycle assessment would capture. Use this as a direction guide, not a precise figure.

How the score is built, since an unexplained number out of 100 is worth nothing

The score is a straight linear mapping: 100 corresponds to zero emissions and 0 to 20 tonnes a year. That upper anchor is deliberate, because 20 tonnes is roughly the top of the range a private individual reaches without owning a jet. It also means the scale is absolute, not a curve against your neighbours. Scoring 80 requires getting under 4 tonnes, which is the global average, and most Americans making every easy change still land in the 40s. That is not a flaw in the scoring. It is the actual gap between an average rich-country life and a globally sustainable one, and softening the scale to make people feel better would defeat the purpose.

The categories are also not equal, and it is worth knowing which lever is real before you spend effort on the wrong one. Ground transport and home energy have the widest spreads here, at 4.9 and 3.6 tonnes between best and worst. Diet spans 3.5. Consumption spans 3.0. A single long-haul flying habit adds 4.5 on its own, which is why one enthusiastic traveller can outweigh every other choice on this page combined.