city growth mechanics

[LlamaCat]

Hey is there written somewhere on here an explanation of how the city growth mechanics work? like specifically I want to know why a particular city would need, say, 25 food to grow to the next size, then later it needs 47 food or whatever... why 25, why 47? are these numbers from complicated calculations based on healthy faces, sick faces, city improvements, etc?

I know that the bigger a city gets the slower the growth, but what are the underlying mechanics of it and the specific numbers? and does knowing this help with long-term planning of deciding what to build in a city?

 

[svv]

The numbers for growth are not dependent on happy/unhappy or sick faces. Unhappy or sick faces would indirectly impact growth by removing food (sick) or making people refusing to work (unhappy) if your unhappiness/unhealthiness exceeds your happyness/health.

I don't know what the numbers for each level are, but I would imagine they are dependent on game speed (you'll need more food stored to grow to the next level on marathon than you will on normal).

 

[OTAKUjbski]

required to grow = 20 + [ population * 2 ]

I believe this changees with difficulty and map size, but I'm really not certain. The formula above is using Warlords 2.08 on Small Prince maps. The essential mechanics are the same though.

Whichever the case building a Granary reduces the requirement by 50% for subsequent growths after it is constructed.

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A city always gets 2 from the tile it is on. You then have a worker you may instruct to work any tile or become a specialist. This is commonly referred to as '+2F'.

Every population point requires 2F to survive, so if you choose to make your 1 worker a specialist, then your city cannot grow (the 2F on your city site are both being used to feed the specialist).

However, if you instruct your worker to work a Floodplain for example, then you will have a surplus of +3F (5F - 2F = 3 toward growth). Thus, your city will grow in 8 turns ( 22 / 3 = 7.34 ).

At Population 2, you second worker might work a 2nd Floodplain to give you +4F (8F - 4F = 4 toward growth). Thus, your city will grow in 6 turns ( 23 / 4 = 5.75 ).

At Population 3, your 3rd worker could be instructed to become a specialist, meaning he eats his -2F and gives you varying benefits depending on his specialization -- leaving +2F ( 8F - 6F = 2 toward growth). Thus, your city will grow slightly slower in 13 turns ( 25 / 2 = 12.5 ).

And so forth and so on.

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Check out this article specifically on "City Growth" from the War Academy:

http://www.civfanatics.com/civ4/strategy/city_growth.php


The next article is focused more on the effects of whipping to boost production -- especially where a Granary is concerned:

http://www.civfanatics.com/civ4/strategy/food_growth.php


This final guide explains how to specialize cities, an artistic science introduced in CivIV. The section "Feeding your City" includes a great way to observe a city's surrounding tiles to help determine its growth and improvement potential:

http://www.civfanatics.com/civ4/strategy/city_specialization.php

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I hope this helps ...

 

[vale]

The numbers are dependent on game speed. As someone above posted 20+2P on normal. It is 30+3P on Epic and 60+6P on Marathon. Quick is a little weird. Because of rounding issues, you have some populations where the food goes up by one from the prior level and some where it goes up by two. I have some numbers for this: Growing from population 5 needs 20 food, 6 needs 21 food 7 needs 22 food and 8 needs 24 food.

I have no idea if map size has anything to do with this although it doesn't seem like it should at all.

Edit to add: I just checked the XML. Map size does not do anything to food requirements.

 

[LlamaCat]

thanks! all very helpful... I'll read up on this

 

[cabert]

vale is right (and the article is right too)

another nebulous matter is the effect of granaries.

I know how it works when your population goes up. Provided the granary's full, you start the next population level with half the food it took to grow. (for example, on normal speed, when you grow from size 1 to 2 with a filled granary, you start at size 2 with 11 food in the growth bar).

I have a hard time understanding how it works on starving population.
Is the granary empty when you lose a pop point?

 

[UncleJJ]

I have a hard time understanding how it works on starving population.
Is the granary empty when you lose a pop point?

Yes it is empty, and you have to fill it up again before it will help with growth. So it takes twice as much food to regain a pop after you have lost a pop due to starvation, but your pop did eat that food so you didn't really lose anything.

 

[VoiceOfUnreason]

A city always gets 2 from the tile it is on.

Obligatory quibble: A city always gets at least 2 food. 3 is possible, if you settle on a tile that has +3F without overlays (in otherwords - a grassland with sugar will give you a 3F city, but a floodplain will not).

 

[OTAKUjbski]

Obligatory quibble: A city always gets at least 2 food. 3 is possible, if you settle on a tile that has +3F without overlays (in otherwords - a grassland with sugar will give you a 3F city, but a floodplain will not).

Orly? I've only settled on top of desert copper (to get the +2F and instant access), so I didn't realize settling on a resource would do this.

Do you also get + and + benefits when settling over a resource bonus?

 

[LlamaCat]

I think in the City Growth article by Tigger70, for that chart, this is interesting to take away:

"Running a surplus 4 or lower for any significant amount of time will yield poor and sub-optimal returns. The 5F to 6F window is entirely satisfactory and maximally efficient. Running a surplus beyond 6F will yield accelerated development, but with a lowered incremental rate of return. Beyond 6F the prospect of utilizing a zero-food citizen becomes notably more reasonable."

so if you want to make long-term plans to grow a city the most efficiently, working the tiles so you have no more than about a 5-6 food surplus at all times would work best.
I am thinking this is good to keep in mind for certain non-specialized cities where you would just want to maybe alternate between building city improvements, units and wonders, but with the overriding goal of growing the city quickly for a later game victory that needs higher population.

I guess those chart numbers are based on epic speed though, since the article focuses on that setting.

 

[VoiceOfUnreason]

Orly? I've only settled on top of desert copper (to get the +2F and instant access), so I didn't realize settling on a resource would do this.

Do you also get + and + benefits when settling over a resource bonus?

The actual mechanic is that you get 2 food, 1 commerce, and 1 hammer unless the initial yield of the tile is higher than that.

Therefore, you can get three food by settling on a food resource on grassland, two coins by settling on a commerce resource next to a river, an extra hammer by settling on a plains hill or a plains tile with a production resource, and two extra hammers when settling on a plains hill with a production resource.