The Nominal National Products of the major powers in 1938, in current dollars:
(1) United States: 84.7 billion
(2) Germany: 46.0 billion*
(3) UK: 27.51 billion
(4) USSR: 23.02 billion
(5) France: 16.18 billion
(6) Italy: 8.68 billion
(7) Japan: 7.49 billion
The per capita figures:
(1) United States: 649
(2) Germany: 590
(3) UK: 579
(4) USSR: 138
(5) France: 385
(6) Italy: 200
(7) Japan: 104
*Note that Germany's figures includes Austria and parts of Czechoslovakia, as they were annexed into the country in 1938.
Using these figures we can estimate the GDP's of the rest of Europe, given that we know the populations and that the levels of development Belgium, Netherlands, Luxembourg, Sweden and Denmark were similar to Germany and the UK (assume per capita income of 500 dollars). Switzerland was richer in per capita income than the US, even in Maddison's GDP estimates (which means that in Market rates the difference was probably greater, assume 700 dollars). Norway and Finland were slightly poorer on average, comparable to France (400 dollars). Spain and Portugal were perhaps on the level of Eastern Europe, Japan and the Soviet Union in terms of per capita incomes (100 dollars).
We also have the per capita income figures for the rest of Eastern Europe (4):
Bulgaria: 99
Hungary: 158
Poland: 132
Romania: 107
Yugoslavia: 105
And their GDP's:
Bulgaria: 0.65 billion
Hungary: 1.45 billion
Poland: 4.63 billion
Romania: 1.67 billion
Yugoslavia: 1.69 billion
total Eastern Europe: 10.09 billion
Note: none of these figures are estimates. These are the actual GDPs of each country converted into dollars using market exchange rates. They show the size of the economy of each country to the international markets. So it measures international economic size/purchasing power. I have compared prices of industrial goods such as steel, machine tools, aircraft and similar items of equipment and they usually match exchange rates. Since munitions are manufactured goods, I think that nominal GDP is a better measure than PPP GDP, unless you wish to count the local purchasing power of prostitution services, housing space and haircuts into our calculations.
Estimated GDP's of other Western European countries:
Denmark: 1.9 billion (assumed per capita income of British/German level, 500 dollars)
Sweden: 3.15 billion (assumed per capita income of British/German level, 500 dollars)
Switzerland: 2.94 billion (assumed per capita income of 700 dollars)
Netherlands: 4.35 billion (assumed per capita income of British/German level, 200 dollars)
Belgium: 4.2 billion (assumed per capita income of British/German level, 200 dollars)
Norway: 1.16 billion (assumed per capita income of French level, 200 dollars)
Finland: 1.48 billion (assumed per capita income of French level, 200 dollars)
Greece: 1.42 billion (assumed per capita income of Italian level, 200 dollars)
Spain: 2.53 billion (assumed per capita income of Bulgarian level, 100 dollars)
Portugal: 0.76 billion (assumed per capita income of Bulgarian level, 100 dollars)
total estimated GDP: 23.89 billion
Western Europe:
23.89 billion (estimated) + 98.37 billion (known) = 122.26 billion
So, in 1938, the World Distribution of GDP was:
Europe: 155.4 billion
--- Western Europe: 122.26 billion
--- Eastern Europe: 10.09 billion
--- Soviet Union: 23.02 billion
United States: 84.7 billion
Japan: 7.49 billion
total: 240.59 billion
Number of countries: 23, 13 known GDP figures, 10 estimated. Though, 90% of the GDP mass was not estimated so the discrepancy with the actual data cannot be too great.
Derived from:
(1) The Economics of WW2, Harrison, chapter 3, page 83
(2) The Economics of WW2, Harrison, chapter 4, page 158, and http://www.paper-dragon.com/1939/exchange.html
(3) http://www.ukpublicspending.co.uk/uk_20 ... chart.html and http://www.paper-dragon.com/1939/exchange.html
(4)

(5) French GDP was ca. 400 billion franks in 1937, exchange rate was 24.72 for the dollar
(6) The Economics of WW2, Harrison, chapter 5, page 179 and http://www.paper-dragon.com/1939/exchange.html
(7) The Economics of WW2, Harrison, chapter 6, page 257 and http://www.paper-dragon.com/1939/exchange.html