This is a short article on settler factories, and how to spot where you can make one.
To make a settler you need 30 shields, and it uses 2 population points. To replace the 2 population points you will need at least 20 surplus food with a granary and 40 surplus food without.
There are 4 basic components to a settler factory
A certain number of “surplus” food.
A spare high production tile. (for additional production on growth)
A certain number of shields per turn at a particular population level
A granary
Only the first 3 are determined by the city’s location, as a granary can be built anywhere.
Surplus food.
A settler factory needs to have either 5 food per turn for a 4 turn settler factory, or 4 food per turn for a 6 turn settler factory. Two of these will be produced by the city square itself, leaving 3 “surplus” for a 4 turn factory and 2 “surplus” for a 6 turn settler factory.
These extra food have to be generated by the citizens working the tiles. This means that extra food is generated by citizens working tiles that produce 3 food or more. Under despotism there are a small number of such tiles, and hence this is usually the limiting factor.
3 surplus food
Irrigated flood plain wheat
2 surplus food
Flood plain wheat
Irrigated Grassland wheat
Irrigated grassland Cow
Irrigated Grassland Game (following a forest chop where the forest reveals a grassland)
Irrigated grassland fish (following a marsh clearance where the marsh reveals a grassland)
1 surplus food
Irrigated Floodplain
City square by a river (agricultural civs only)
Irrigated cow on plain
Irrigated wheat on plain
Irrigated Game on plain
Fish in lake
Irrigated wine on grass
Grassland wheat
Grassland cow
Grassland game (following a forest chop where the forest reveals a grassland)
Grassland fish (following a marsh clearance where the marsh reveals a
A spare high production tile
When a city grows and a new citizen is added, if you have the governor set to maximise production but turned off, it will be added to the highest producing square available and the shields will be added on that same turn.
This means that having a spare forest or mined plain around will produce 4 of the 30 shields required for the settler.
Production at a particular population level
The highest population level at which a settler factory can start the cycle is 5 (4 if you have no access to fresh water) . It will then spend half the turns (i.e. 2 for a 4 turn settler factory or 3 for a six turn settler factory) at that level, and the other half at population 6. Then it will grow and produce the settler at the same time and be back down to 5 with the granary still full. This seems like magic the first time you do it, but it does work.
It does however require disciplined micromanagement.
Requirements for a 4 turn settler factory
For a 4 turn settler factory you need 6 production after waste at your starting population while working all the bonus food and 7 at one higher than your starting population. This assumes that you have a spare forest or other 2 shield producing somewhere. Your shields will then be 6 on the first turn, 6 on the second turn, plus the extra 2 from the newly produced citizen, 7 on the third turn, and 7 plus 2 on the final turn.
The other alternatives are
7 production at your starting population and at your starting population plus one, and also having one additional shield producing tile.
6 production at the starting population and 8 at the starting population plus one.
Example of a 4 turn settler factory
One example would be
using the capital so that there is no waste of shields,
Irrigated cow on grassland – 2 surplus food, 1 production
Fish in a lake – 1 surplus food
2 mined bonus grass land – 2 production each
a mined grassland (worked in turns 3 and 4)
a forest (used in turns 2 and 4)
This together with the 2 food and 1 shield produced by the city centre is sufficient.
The city starts off at population 4, produces 6 shields in turn 1, produces 6 shields in turn 2 plus 2 more from the forest as it grows to turn 5, produces 7 in turn 3, and 7 in turn 4 and grows, produces the last 2 shields from the forest produces a settler and will drop back down to size 4.
You will have to move the citizen away from the forest onto the mined grassland at the start of turn 3 (otherwise you will only get 4 food) and again on turn 1.
Also just before you press enter to end turn 4 the city will show grows in 1 produces settler in 2. Don’t panic. This does not take into account the 2 shields that you will get from the growth.
Out of phase settler factory
In the above examples the settler is produced on the same turn as the city grows. This means that city growth happens on turns 2 and 4 of production.
It is also possible to work a settler factory where growth occurs on turns 1 and 3. Here the city will be at its starting level of population(e.g. 4) for 1 turn, one above that for 2 turns, and one above this for 1 turn. Clearly in this case 4 is the maximum starting population. You will still get 2 lots of extra shields from the population grown turns, so if you have a spare forest you need to find a further 26 shields of production. In practice as long as you can get 7SPT at size 5 and have a spare forest it should work.
Requirements for a 6 turn settler factory
As stated above you need 2 surplus food for a six turn factory (e.g. an irrigated wheat on grassland on its own), and
4 production at your initial level and 5 at one pop higher, plus a spare forest, or
5 production at both levels.
There is more flexibility however, as you can do without your food bonus every third turn
Requirements for a “combo” factory
For a 6 turn factory the trick is to build a 10 shield unit in the first 2 turns of the cycle and the settler with the remaining 4. This needs 5 SP at the starting pop level and 7SPT at the higher level, together with a forest. A 4 turn combo factory is also possible but that needs 10 spt at pop 5 so it is rarely possible!