Treemap of World GDP by Purchasing Power Parity (PPP) 2020 (opens in new tab)

To take a example that is currently of interest, Russia's ability to manufacture weapons is far greater than that if a country with the same nominal GDP but is closer to its PPP GDP (plus the effects of being more self sufficient than most countries other than the big two).

I agree. As I commented recently here, we should also normalize by total hours worked. People in the US work much more than in many other countries.

I guess one use of total GDP adj. b. PPP would be when countries negotiate something. Then, China would have a strong argument for setting terms.

Depends on what you want to compare.

If you want to understand the "heft" of the country in terms of the sheer size of the economy (adjusted for exchange rates) then you do country GDP on PPP basis.

If you want to understand the size taking into account currency rates then you do plain GDP.

If you want to understand how well off a citizen is THEN you do per-capita GDP.

When countries play on the world stage for influence, their overall heft i.e. total GDP (whether on a PPP basis or not) is essentially the main determinant.

The treemap shows how global total purchasing power is divided between countries.

A treemap of GDP PPP per capita would show the breakdown of purchasing power if you put one citizen of each country in a single room. I think a bar chart would be a better choice in that case.

I don't think anyone here believes China is ahead in terms of average standard of living. This graphic is just about the overall size of the economy.

In case of adverse currency move, EU, Russia and China may still produce as much stuff (taken together they produce all of the components, whose effective price unchanged), but their US competitors are all undercut on price. They'll consume a bit less for the duration, though.