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Revision as of 20:11, 29 December 2018 by Y1kdcb5au9rqw (talk | contribs) (Starbase Capacity)


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This article is for the PC version of Stellaris only.
Mammalian Citadel
For the construction of civilian ships see Spaceport.

A starbase is the primary space station used throughout the game. Its main functions are: determining the ownership of star systems, construction of military ships, ship repair, and strategic fort-like use during warfare.



A starbase's most fundamental function lies in asserting ownership over star systems. Doing so requires fully surveying the desired system and an additional varying   influence cost (on top of the regular mineral costs). The influence cost is determined by a fixed cost multiplied by the shortest path of hyperlane jumps (gates and wormholes act as "shortcuts") between the target systems and the empire's closest owned system.

Once built, the starbase will appear orbiting the center point of the system. It cannot be destroyed by any regular means, however, it may still be dismantled if it is controlled by its owner, done during peace time, and the starbase in question is an outpost level (may require level downgrading).

Besides the initial influence cost, upgrading the starbase to one of a higher level will cost only alloys and time. Aside from making the starbase more powerful due to better base stats and increased component slots, the upgrade also allows to fit the starbase with different buildings and modules increasing its contribution to the empire beyond its basic role of system control. One such important module is the   Shipyard which enables the construction of military ships in the starbase. Having multiples of this module allows a starbase to effectively act as a "fleet manufactory" by constructing several ships simultaneously. Shipyards build order is independent from the main build order of starbase.

Though it is not possible to design a starbase, its components will be auto-fitted with the latest advanced technology as soon as they are made available (at no additional cost to the owner).

Warfare behavior

Systems with upgraded starbases require higher influence cost to claim (25 influence) than simple outposts. Consequently, those starbases grant a higher war-score if occupied successfully (10 occupation value). An additional benefit of upgraded starbases manifests in them including an FTL inhibitor. Such an upgraded starbase can turn strategically important systems into efficient choke points, delaying hostile fleets from leaving the system and advancing further by forcing them into an engagement which may last long enough for reinforcements to arrive.

During war, it is required to disable the enemy's starbase within the system in order to seize control of their planets. As starbases cannot be destroyed, this is achieved by reducing them to   0 Hull points. The starbase will remain incapacitated for a duration of   30 days (after the latest attack), during which time any military ships in close proximity to the starbase will be able to gain control over it. If the starbase is left unoccupied and without a ship attacking it from time to time, it will enter a self-repair phase and become operational again as soon as it regains   5% Hull points. Occupier empire is assigned depending on claims, e.g. it will be transferred to the ally with the strongest claim, even if conquered not by them.

Occupied starbases are fully operational and can repair occupiers ships, inhibit FTL, and manage defense platforms, all empire-wide bonuses also will be applied, including home territory (Eternal Vigilance perk's platform cap of original owner is also temporarily retained). However their buildings and modules cannot be changed, and they cannot be upgraded or downgraded, although they can be returned back to the owner.

It worth noting, that auto-upgrading can "gift" higher tech components to occupied starbases (including FTL inhibitors!), while keeping their own more advanced components. They will stay equipped even if starbase is reclaimed back, so repeated re-conquering might be slightly more challenging to the both sides.

Systems containing an unoccupied starbase or unoccupied colonized planets will not be transferred in a forced status-quo peace.

Starbase Capacity

Although it is possible for an empire to have a high number of starbases, it can support only a limited number of them above the outpost level. Exceeding the capacity will result in +25%   Upkeep per starbase exceeding the cap. This is an empire modifier, and thus affects all of that empires starbases, this also factors in the maintenance of any modules and buildings on their starbases. Regardless of their level, each starbase above outpost level occupies only one capacity slot.

The base Starbase Capacity is 3, which can be increased by the following:

  • +1 per 10 systems in the empire
  • +2   adopting Supremacy tradition tree
  • +2   Galactic Ambitions technology
  • +2   Manifest Destiny technology
  • +4   Trading Posts civic
  • +5   Grasp the Void ascension perk
  • +10   Covenant: End of the Cycle
  • +1   Interstellar Expansion repeatable technology
  • +2 for each Strategic Coordination Center level


A starbase is auto-fitted with the latest components as soon as they are available to the empire. This is done automatically and has no additional cost for the empire - as such this also does not affect a starbase's level upgrade cost.

The weapon slots are fitted with the most effective kinetic and energy weapons (though not necessarily by equal division). The utility slots are divided equally between   shield and   armor components (auto-fitting does not add hull components here), while the auxiliary slot uses standard auto-fitting of a shield capacitor or auxiliary fire-control (whatever is available in order of priority).

Upgrading a starbase can only be done in a sequential order - meaning, one would require to upgrade through all the levels in order to get to the highest level available. Downgrading a starbase, however, reduces its level to the basic level (outpost) straight away - regardless of what level the starbase was - and removes any present buildings, modules, and any defense platforms over the outpost's capacity limit.

Starting from the starport level all starbases can repair parked ships (shipyards are not required) and   inhibit FTL if technology is available.

Note: The table lists the base properties of each starbase level. The actual values themselves will differ due to one's progress in-game (technology, tradition, and etc.) as well as individual starbase composition (buildings, modules, and etc.).

Starbase Level Cost Slots Military properties Requirements Description
      M B D     Weapons Utilities
  Outpost 0 100 100 1 0 0 3 5000 1000   1   2
  •   Starbase Construction
  •   75 Influence per hyperlane jump (from closest owned system)
The most basic kind of Starbase, Outposts are lightly-armed stations built in stellar orbit to extend national borders. Outposts can not support any Buildings or Modules and are not listed in the Outliner.
  Starport 1 200 360 2 2 1 6 10000 2000   2
  •   Starport
  •   Outpost
Upgrading the Outpost, Starports can house one Building and support two Modules.
  Starhold 2 500 720 3 4 2 9 20000 5000   4
  •   Starhold
  •   Starport
Upgrading the Starport, Starholds can house two Buildings and support four Modules.
  Star Fortress 3 1250 1080 4 6 3 12 40000 10000   6
  •   Star Fortress
  •   Starhold
Upgrading the Starhold, Star Fortresses can house three Buildings and a full complement of six Modules.
  Citadel 4 3500 1440 5 6 4 15 80000 20000   12
  •   Citadel
  •   Star Fortress
Upgrading the Star Fortress, Citadels are the largest and most heavily fortified type of Starbase and can house four Buildings and a full complement of six Modules.

Affecting modifiers

Additional modifiers which affect various starbase parameters are summarized below:

Construction and maintenance modifiers
  Outpost influence cost
−50%   Devouring swarm
−40%   Fanatic xenophobe
−30%   Determined exterminator
  •   Xenophobe
  •   Interstellar Dominion
−15%   Expansionist
−10%   Reach for the Stars
−5%   The Chosen
  Outpost build cost
−15%   Expansionist
  Upkeep cost
−20%   Galactic Ambition
−10%   Administrative Operations
+25% "Exceeding starbase capacity" modifier
Upgrade related modifiers
  Upgrade cost
−20%   Supremacy tree adoption
−15%   Corps of Engineers
  •   Fortifier
  •   Home in the Sky
  Upgrade speed
+100%   Fortress Proclamation
+25%   Corps of Engineers
Military properties related modifiers
+25%   Eternal Vigilance
  Hull points
  •   Gun Battery
  •   Hangar Bay
  •   Missile Battery
  •   Never Surrender
  Armor hit points
  •   Gun Battery
  •   Hangar Bay
  •   Missile Battery


A fully upgraded starbase can support up to 6 modules. It is possible to construct multiple modules of the same type.

  Modifiers affecting module build cost include:

  • −25%   Modular Engineering
  • −20%   Home in the Sky
  • −10% "Zero-G Innovations" modifier
Module       Effects Requirements Description
  Anchorage 50 180 1   +4 Naval capacity Fleet anchorages are necessary to support the growth of our navy.
  Gun Battery 50 180 1
  •   +2 Medium weapon components
  •   +5 Trade Protection
  •   +1 Protection Range
  •   Starbase and platforms gain:
  •   +10% Armor hit points
  •   +10% Hull points
  Mass Drivers Adds two medium-size weapon slots to the Starbase.
  Hangar Bay 50 180 1
  •   +1 Hangar weapon components
  •   +10 Trade Protection
  •   +1 Protection Range
  •   Starbase and platforms gain:
  •   +10% Armor hit points
  •   +10% Hull points
  Carrier Operations Adds a hangar for strike craft to the Starbase.
  Missile Battery 50 180 1
  •   +2 Guided weapon components
  •   +5 Trade Protection
  •   +1 Protection Range
  •   Starbase and platforms gain:
  •   +10% Armor hit points
  •   +10% Hull points
  Nuclear Missiles Adds two torpedo weapon slots to the Starbase.
  Shipyard 50 180 1 +1 Shipyard capacity increase A Shipyard may build one ship at a time, in parallel with other Shipyards.
  Solar Panel Network 50 180   +3 Energy
  •    Gestalt Consciousness
  • Orbital Energy Conversion
Advances in solar panel technology cound offset the operating costs of our starbases.
  Trade Hub 50 180 1   +1 Collection Range    Gestalt Consciousness A civilian docking area where merchants and traders can conduct business.


A fully upgraded starbase can support up to 4 buildings. Unlike modules, it is only possible to construct a single building of any type.

  Modifiers affecting starbase building build cost include:

  • −25%   Modular Engineering
Building       Effects Requirements Description
  Art College 200 360 2 +10   Unity   Governing ethics attraction
  •   A diplomatic agreement with the in-system Artisan enclave
  •   Is not:
  •   Gestalt Consciousness
  •   Fanatic Purifiers
This zero-g Art College, operated in conjunction with the nearby Artisan Enclave, celebrates the beauty of outer space in the works produced by its talented students.
  Black Hole Observatory 100 360 2 +10   Physics research
  •   Subspace Sensors
  •   System contains a black hole
By building a specialized science facility dedicated to studying a black hole, our empire will surely be able to see improvements in our understanding of Physics.
  Colossus Assembly Yards 1000 720 20   Colossus construction enabled in   Shipyard
  •   Colossi
  •   Citadel
  •   Shipyard
Abandoning the traditional concept of drydocks, Colossi are assembled by a number of highly mobile independent construction platforms.
  Command Center 250 360 5
  • Defensive aura:
  • +10%   Fire Rate
  •   Command Matrix
  •   Star Fortress
All system defense efforts are coordinated from this large facility, buried deep within the hull of the Starbase. Map arrays and 3D projections track all space traffing passing through the system at any given time.
  Communications Jammer 50 180 1
  • Offensive aura:
  • –20% Combat disengagement chance
  • –20%   Sublight speed
These powerful jammers interfere with enemy ship-to-ship communications, making it difficult to coordinate fleet movements.
  Crew Quarters
  Crew Gestation Chambers
50 180 1 –25%   Docked ship upkeep Provides accommodation and support for spaceship crews, reducing the logistical burden on fleets that are berthed here.
  The ability to birth and gestate crew drones directly on-site is a logistical boon to local fleets.
  Curator Think Tank 100 360 2 +5   Research
  •   A diplomatic agreement with the in-system curator enclave
  •   Is not:
  •   Determined Exterminator
  •   Devouring Swarm
  •   Fanatic Purifiers
By constructing a research facility entirely focused on learning from, and cooperating with, the Curators, we are able to make significant contributions to our scientific progress.
  Deep Space Black Site 100 360 2
  • +1   Unity
  •   System gains:
  • +25%   Governing ethics attraction
  • +5   Stability
  •   The Living State
  •   System is colonized
  •    Gestalt Consciousness
A large part of this Starbase has been set aside as a Black Site that does not officially exist. The entire system is closely monitored from here, while intelligence operatives carefully manipulate local media and social events to the best of their ability.
  Defense-Grid Supercomputer 150 360 2 +8   Starbase defense platform capacity   Synchronized Defenses A powerful supercomputer coordinating the relative orbit and firing arcs of the Starbase's defensive platforms, increasing the number of defensive platforms that can be supported.
  Disruption Field Generator 100 180 2
  • Offensive aura:
  • –20%   Shield hit points
Generates localized fields of agitated subatomic particles around hostile ships in the system, significantly reducing the effectiveness of their shields.
  Fleet Academy
  Battle Simulators
100 360 2 +100   Ship starting experience
  •   Interstellar Fleet Traditions
  •   Shipyard
For our newly recruited crews to be truly combat ready, they must have capable officers leading them. The Fleet Academy will ensure those officers have up-to-date knowledge on the doctrines and practice of interstellar warfare.
  Repeated simulation of various battle scenarios will better prepare our shipboard combat drones for real combat.
  Hydroponics Bay 50 180 1 +3   Food Hydroponic Farming Tech By dedicating a section of this Starbase to Hydroponic farming, the station will be able to feed itself and even export excess produce to other systems.
  Hyperlane Registrar 100 180 2
  • Defensive aura:
  • +20% Combat disengagement chance
  • –20% Jump charge time
  • –20% Jump cooldown
  Hyperlane Breach Points Assists friendly ships in the system with FTL travel by identifying ideal conditions for entering the hyperlanes and optimizing projected travel routes.
  Listening Post 100 360 2 +2   Sensor range
+4 Hyperlane detection range
  Gravitic Sensors The Listening Post houses a team of dedicated operators tasked with analyzing hyperlane reverberations, functionally extending the range of the Starbase's sensors.
  Nebula Refinery 100 360 2 +6   Minerals
  •   Mineral Processing
  •   System is inside a nebula
By processing the dust clouds of a nebula, we are able to refine and extract valuable minerals.
  Offworld Trading Company 100 360 0 +2   Trade Value from   Trading Hub
  •   Space Trading
  •    Gestalt Consciousness
  •   Trading Hub
The offices of a non-governmental organ dedicated to improving the conditions of interstellar trade.
  Resource Silo 50 180 0
  • +2000 Resource storage capacity
Massive resource silos and energy storage facilities where large quantities of minerals and energy can be safely kept.
  Titan Assembly Yards 500 720 10   Titan construction enabled in   Shipyard
  •   Titans
  •   Citadel
  •   Shipyard
Specialized drydocks erected on the Starbase's hull allow for the construction of gargantuan Titan-class ships.
  Trader Proxy Office 100 360 0 -5%   Market fee
  •   System has Trader enclave
  •   Is not:
  •   Gestalt Consciousness
  •   Fanatic Purifiers
The Trader Enclave enjoy special privileges on the Galactic Market, which can also benefit us.

Defense platforms

A starbase's self-defense capabilities can be further reinforced with the construction of defense platforms. These platforms are smaller military stations deployed around the starbase. They will engage any incoming hostile forces, effectively acting as a buffer, by attacking and distracting them from focusing their efforts on the starbase itself. When compared with ships, platforms are situated between destroyer and cruiser classes, their hull and armament slightly better than the first, while armor-potential is equivalent to the latter. However, due to them having no evasion whatsoever, individual platforms are still very vulnerable, and if a strong, sustainable firepower is a priority it is wiser to put more turrets on the base itself.

As opposed to the auto-fitting of the starbase's components, defense platforms can be altered through the ship designer allowing for several designs to be built based on the different needs in each front and upgraded based on this designs. However, unlike ships, their designs cannot be switched once built, necessitating dismantling and complete rebuilding. It also renders any transferred platforms non-upgradeable. Economically defense platforms are, again, comparable to destroyers, but they cost no minerals upkeep.

Each starbase can support only a certain number of defense platforms based on its level. However, the defense platform capacity can be increased with the following:

  • Globally: +5   Eternal Vigilance
  • Locally: +8   Defense-Grid Supercomputer , +4/+8/+12  Strategic Coordination Center galatic wonder

In addition to the regular defense platforms, a more powerful platform type may be constructed equipped with an Ion Cannon weapon (once the required technology has been researched). This platform type carries a singular weapon, identical to the Perdition Beam weapon and which can not be changed, capable of engaging enemies from further away. It is titan-class hull-wise, although armored only as battleship, economically it also comparable to the latter without mineral upkeep, and it is deployed quite slowly.

An ion cannon platform occupies 8 defense platform capacity slots and can only be constructed by citadel level starbases.

Defense platform modifiers

Additional modifiers which affect various defense platform parameters are summarized below:

  •   Eternal Vigilance
  •   Secure the Borders
+10%   Synchronized Firing Patterns
  Hull points
+25%   Secure the Borders
+20%   Armed Deterrence
  •   Fortified Core Layers
  •   Gun Battery
  •   Hangar Bay
  •   Missile Battery
+500   Improved Structural Integrity
  Armor hit points
  •   Gun Battery
  •   Hangar Bay
  •   Missile Battery
  Build cost
−33%   Fortifier
−25%   Armed Deterrence
−15%   Secure the Borders
  Build speed
+100%   Fortress Proclamation