Upvote:1
According to the data from Maddison you might make your guess using information from year 1820.
In millions:
United Kingdom: 36,232
France: 35,468
Prussia: 26,819 (surely less, because it covers all present German territory); perhaps half this or a little more.
Russia: 37,678 (probably less, because it covers all former Soviet Union territory)
Austria: My guess is near 20,000 (data shows info from current European countries)
Holland: 4,288
Spain: 12,299
Denmark: 1,471
United States: 13,499
China: 228,600
Ottoman Empire: My guess is close to 14,000
Maratha Confederacy: 111,417 (far less, probably half of this, because it covers probably the whole indian subcontinent)