Crusader Kings In depth guide to Development By: SagaciousElan


The game has been out for over 6 months now and there’s a fair amount of information out there by now but at one point I decided I wanted to really focus on development and see how far I could take it. I’m not the greatest of optimisers but I figured I wasn’t going to get very far unless I could really figure out how the system worked, so here are a few bits and pieces I’ve learned:


Every county in the game has a development score between 0 and 100. The wiki lists the starting development of every county in the game as at the 867 start and the 1066 start. Constantinople is typically the highest development county in the world in the absence of a concerted effort by the player. Rome is typically second, Cordoba third and there are also several contenders in India around the Ganges and down south in Madurai.

You want to have as much development as you can get. There are no downsides to high development. It speeds up your technological progress and it boosts your income. Specifically, the increments by which your culture researches new technological innovations are determined by the average development of all counties of your culture. The culture head’s Learning an perks will determine the percentage chance of increasing progress towards technological innovations but average development determines how much progress is added each time it triggers.

Neighbouring counties

Development bleeds across county borders and the lower development county receives a bonus to its monthly development based on the difference in relative development between it and the counties around it. A county with 10 Development next to a county with 15 development will receive 0.5 development growth each month until it reaches 11 development, then 0.4 per month and so on until it fully catches up. However, a county with more development than any of its neighbours will not increase at all on its own. Another source of development growth is required.

Raw development growth

It is important to note that there is a difference between raw development growth and percentage development growth which is that percentage development growth does nothing on its own. A maxed out Guilds building in a city give +40% development growth to the county it is in, but if the raw development growth is 0.0 then an extra 40% of that is still nothing. Aside from neighbouring counties there are only 2 sources of raw development growth: the Steward’s Increase Development task or a special building. The Increase Development task provides raw development based on the Steward’s skill and certain special buildings provide a fixed amount of raw development. For example, the Visby Ringmur special building provides 0.2 raw development per month as well as a 15% percentage increase to development. Any county with a special building with a raw development bonus will naturally grow over time and bring the counties around it up too.

Existing development

Additionally, raw development growth is reduced by an existing development penalty. The closer a county’s total development score is to the cap for the era that culture is in, the higher the penalty. Also, percentage based growth bonuses apply after the final raw score is worked out. For example, a county with a raw growth amount of 2.7 per month and an existing development penalty of -2.5 will have a growth amount per month of 0.2. If it also had a total of 150% bonus development growth then that is applied to the 0.2 figure for a final amount of 0.5 per month.

Percentage development growth

Once you have your raw development above 0.0 then you want to stack as many percentage growth bonuses onto it as you can. There are multiple sources of development percentage bonuses. These include terrain, buildings, special buildings, lifestyle perks, dynasty legacies, random events and probably more. Almost all percentage development growth bonuses stack with each other.

Early on, the highest percentage bonuses are going to come from terrain and special buildings. Late game, they are going to be far outstripped by buildings. The two best buildings by far are Guilds and Tradeports as each provide a 5% development growth boost per upgrade level, each maxing out at 40% when fully upgraded. There are a couple of special buildings like the Buddhas of Bamiyan which provide a 75% increase but they are unique and often they are only barely counteracting the -50% development penalty for being situated in Mountain terrain.

Terrain and buildings

For terrain that boosts development you want Farmlands or Floodplains which both give +20% while Oasis gives +10%. Those are the only terrain with a bonus while Forest and Plains are neutral and every other type gives you a penalty. Bear in mind that only the barony with the capital castle on it matters for development any other baronies are irrelevant. Somewhere like Roma with 6 Farmland Baronies is no better in terms of getting a 20% bonus for the capital being Farmland than Napoli which has 2 baronies and only one of them is Farmland.

One thing which is less obvious than what terrain the capital is on is how many baronies in the county have coastline. Coastline allows you to built the Tradeport building which is possibly the single best development building in the game. Like fully upgrade Guilds, a fully upgraded Tradeport gives a 40% boost to county development as well as some gold income. Unlike Guilds, which can only be built in cities, Tradeports can be built in cities and temples and castles as well, so long as the relevant barony is on the coast. This means that a coastal city can have both a Tradeport and a Guild for an 80% development growth bonus from a single barony.

The only possible rival for the Tradeport as best development building is the Royal Reserves. As a duchy building you can only build one of it in the duchy capital. Since you can only have 2 duchies without penalties you probably won’t have more than 2 of them in your realm. The thing which sets it apart though is that the percentage bonus it gives, which is 30% at max level, applies not only in the duchy capital but in every county in the duchy so building one in West Franconia gets you a 30% bonus in 9 counties at once. The size of your duchy will determine how worthwhile it is and how it stacks up against other duchy building options but it shines in large duchies.

Perks and Legacies

Terrain and buildings are great but they are (mostly) limited by geography. They apply where they are and nowhere else. Even the Steward’s Increase Development ability can only be applied to one county at a time. Perks and legacies though, are more flexible. There are a few lifestyle perks which relate to development. Centralisation from Stewardship’s Architect tree grants 0.3 raw development growth in your realm capital. Planned Cultivation in Learning’s Scholar tree makes your Steward’s Increase Development task 15% more efficient. Both of those still only apply to one county though. The Scholar trait at the end of the Scholar tree though, grants you a 15% development growth bonus. As a character trait it’s not clear what that means for you as a person, but it does apply a 15% bonus to every single county you rule, meaning your entire domain. Similarly the 3rd perk in the Erudition dynasty legacy grants a 20% development growth bonus which applies not only to you and every county under your rule, but to every county under the rule of anyone in your dynasty which if you’ve managed to spread your bloodline around a bit could be quite a large area. For sheer reach that is probably the biggest single bonus to be found in the game but it is spread out across many counties rather than concentrated in your capital where you probably want it.

Case study

For your consideration I submit the county of Sjaelland as one of the best places for cranking your development engine up. Sjaelland is a 5 barony county with its capital castle on Farmland terrain and all 5 baronies are coastal. It is also the duchy capital of the Duchy of Sjaelland and the de jure capital of the Kingdom of Denmark. At release it was an Asatru holy site so it also had a special building slot for a Grand Temple which would have added another 20% and 0.1 raw monthly development. After Northern Lords that honour has been taken over by nearby Skane which now has the Lund Cathedral for Christian rulers. Skane is almost as good a county as Sjaelland, also having 5 baronies but only 4 of which are coastal and it is not as central to the de jure kingdom for the purpose of development radiating outwards into neighbouring counties.

With 5 baronies we need a minimum of 1 castle, 1 temple and 1 city, meaning we have 2 extra baronies to play with. Since we are going for development we want to build cities since only cities can have Guilds which give a 40% bonus each. So we want to have 1 castle, 1 temple and 3 cities.

All of the baronies are coastal so we will build a Tradeport in all 5 of them. That’s 40% development growth per Tradeport = 200%, plus another 120% for having 3 guilds in our 3 cities. Add to that 20% for the castle being on farmland and we’ll build a Royal Reserve in the Duchy slot for another 30%. If our ruler has the Scholar trait he adds another 15% and the Erudition dynasty legacy adds another 20%. That’s a total of 405% bonus growth.

If you’re crazy lucky or luckily crazy there’s one more option: the Glass Monument. This is a random event for characters with the Lunatic trait and it is amazing. If you get the event and build the building, the Glass Monument appears in your capital. It doesn’t take up a slot because it adds a new slot and it gives your character +1 monthly prestige and a small health boost as well as giving the county +1 gold per month, +25 public opinion and most importantly, 25% monthly development. It’s like a special building you can build anywhere which gives you money, boosts your development and makes your characters live longer. It’s amazing.

The glass monument brings our hypothetical Sjaelland up to +430% monthly development. Add to that the fact that Denmark isn’t a huge country and it has its own unique and fairly small culture and it has the makings of a development powerhouse. Compare it to Byzantion which is a one barony county on farmland, on the coast with some special buildings. Start with 20% for Farmland, build a Tradeport for 40% more, add +20% for the Theodosian Walls, 15% Scholar bonus, 20% Erudition perk and 25% for a glass monument and that’s about it. You can’t have a Royal Reserve because the walls take up the duchy slot and you can’ t have any more ports or guilds because the county is too small. The 0.3 raw development from the walls probably tip the scales a bit but comparing 140% to 430% it’s pretty clear that Sjaelland will catch up fairly quickly and overtake Constantinople in no time.


Hopefully that was helpful to someone out there trying to figure out this crazy system and maybe there’s one thing in here which was new to you even after many hours of conquest and politics!

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