Okay, in this topic I will calculate all usages for the all resources: coal, iron, oil, uranium, food and refined ones: steel, lead, munitions and aluminium.
The resources which I talk about is unrefined ones: coal, iron, oil, uranium and food.
The basic 2 resources you will get is coal and food (or oil/coal in North America and other continents which don't support coal). Because of this both 2 coal/oil have advantages and disadvantages. Advantage in oil is that it can be easily used to oil power plants, which is cleaner, letting more infrastructure at cost of population density and disease rate.
Okay, then if you build a coal mine (2 is enough) and a power plant (1 is enough, 2 is over enough since you will need 1 coal plant per 500 infrastructure), they will give you coal and power. Except of course will give reduced rate due to usage of the coal by the power plant. If we use basic economics to demonstrate this: 0.1/turn = 1.2/day usage of coal to the power plant and:
0.5/turn = 6.0/day mine of the coal: so you end having 4.80 coal at the end of the day (which is enough), or lower if you have 2 power plants which you should multiply:
2x0.1=0.2x12(turns in a day) = 2.4 coal usage, but you still have 3.6 coal at the end of the day and the maximum third:
3x0.1=0.3x12 = 3.6 coal usage, which is slightly more than you get coal. So if you have 2 coal mines and three power plants, you better get another one ASAP.
Now there's a exception. If you have 2 cities with all 3 coal plants each, they will don't use the city's ''production''. They will all use from the stockpile and use resources which is produced by another city. So for example, if City A produces 3 coal mines and has 3 coal plants, and City B has 3 coal plants and no coal production, it will not be inactive. It will still use from the City A, which in math, looks like this:
In turns:
0.3 (City A) + 0.3 (City = 0.6 x 12 = 7.2 coal (enough for 3 coal mines)
In days (both coal plants):
7.2 + 7.2 = 14.4 coal used per day (enough for 3 of course)
And with more cities, you add more usage for 3 power plants. Now let's look at City A/2 coal plants and City B/1 coal plants. It's same except you reduce the usage of Country B.
This same applies to power and refined resources. For example steel works the same way, except you of course need the another building. But what about food?
Food farms is affected by the land area. So if you have 1,000 square miles with 8 farms, it's lot more effective than with 800 square miles. Now here is things get slightly harder: the production of food per square mile and the usage of the military affected by it. It's affected that you get 0.5 food per square mile. Which if you calculate your country's square miles and 0.5, you get your production rate. In my nation, as 777 square miles (unlucky), if I multiply by 0.5, I get about 388.5 food/day. The next step is usage of your military. In this case, I have 3,000 soldiers, so in peacetime I would only use about 4 food per day? Is that hypothetical? Well, there are more factors which use food which I will don't mislead into this comment, maybe tomorrow. And in wartime it would cost 6 food per day. So effectively, wartime adds 0.5 more money and food than in peacetime. I hope you understand mathematics in this post, if you don't understand something feel free to ask me. It's really appreciated to let newbies understand the game.
Sincerely,
Nathan