A country’s overshoot day is the date on which Earth Overshoot Day would fall if all of humanity consumed like the people in this country.

We determine this year’s country overshoot days using the National Footprint and Biocapacity Accounts’ edition of the prior year. By locking in the overshoot date based on the prior edition, we can provide country overshoot days earlier in the calendar year while also maintaining data consistency for all countries. It also avoids suddenly switching the dates as a new edition of the National Footprint and Biocapacity Accounts becomes available (typically in the spring). Therefore, country overshoot days for 2020 are based on the 2019 edition. The 2019 edition features Ecological Footprint and biocapacity data from 1961 to the latest data-year of 2016. Typically, there is a two to four-year lag between the latest data-year and the present due to the UN’s reporting process.

Let’s take Switzerland’s 2020 overshoot day, for example, using the 2019 edition (with data for 2016):

The Ecological Footprint for Switzerland is 4.64 gha per person (in 2016)

per person (in 2016) Global biocapacity is 1.63 gha per person (in 2016)

Therefore, it would take (4.64/ 1.63) = 2.8 Earths if everyone lived like the Swiss,

OR

we can determine Switzerland’s overshoot day, given that 2020 is a leap year, as 366 * (1.63/4.64) = 129th day in the year. The 129th day of 2020 is the 8th of May, Switzerland’s Overshoot Day.

Not all countries will have an overshoot day. By way of the country overshoot equation above, a country will only have an overshoot day if their Ecological Footprint per person is greater than global biocapacity per person (1.63 gha). Countries whose Ecological Footprint per person are less than global biocapacity per person (1.63 gha) and do not have an overshoot day are therefore not included in our list below. In leap years, we compare the date against 366 days of the year, rather than the usual 365.