Some of these are measured country averages with a modelled spread; some are modelled from another measure; one is a single world estimate. The grade says which, and the page says exactly what is assumed.
No. A percentile says where a number sits in a population; it says nothing about your health or what you should do. BMI in particular cannot tell muscle from fat, and a healthy weight depends on much else. For your health, ask a doctor; for your money, a qualified adviser.
The public country datasets give the average height or BMI of a country, not the full spread. The page assumes the spread is a fixed proportion of the average (4% for height, 16% for BMI, typical of survey data) and says so. That is accurate in the middle, and least accurate in the far tails.
The World Bank measures the income, or the consumption where income is not surveyed, of a household divided by the people in it, counting children, in dollars adjusted so a dollar buys the same in every country (2021 prices). It is not an individual salary: a couple earning £80,000 with two children is £20,000 a head. The page converts your local figure at your country’s own price level.
No open table gives the wealth of each country’s adults. The page fits one world curve to two published facts: just over 41% of adults hold under $10,000, and total household wealth divided by adults is about $90,000 each. The curve is therefore only good in the middle; it understates the very rich, so a big fortune is ranked on the safe side.
Nobody publishes the distribution of individual footprints for every country. What exists is each country’s average per person, so the page ranks you against those: “people in countries holding X% of the world use less than this”. A rich person in a poor country, or the reverse, is not captured.
Age adjustment: height and BMI are shown for adults of your sex, not your age band, and the 18-year-old height of the 1996 birth cohort is used for adult height. Waist is not here because no open source gives a waist distribution by country. Verified in percentile_model.py.
It does not mean 84 out of 100 marks. It means that out of every hundred people, 84 have a lower value than you. The 50th is the median: half below, half above.
A man of 178 cm is taller than about 84% of the world’s men and not much above the middle in the Netherlands. The world is a mixture of countries with different averages, so the same height sits at different percentiles depending on the pool you are compared with.
Mean income is always above the median, because a few very high incomes pull it up. The bigger the gap between them, the more unequal the country; the page builds each country’s curve from exactly that gap.
Your country’s carbon footprint per person is the national total divided by everyone. It includes the power station and the steelworks you never visit, and leaves out what is made abroad for you. It is a fact about the country, not your life.
This page has changed in 55 archived releases, but each of those was a site-wide pass, so none is attributable to this tool on its own and none is listed here. That is not a claim that the tool never changed — a release that reworked many pages at once may well have altered this one too. The changelog has them.