Ship size classes

X4 ships come in 5 size classes — class.ship_xs through class.ship_xl. These are not separate datatypes; all five share the Ship datatype. The size class is a class label used by find_* filters and game mechanics (boardable vs not, fits-in-dock-size, etc.).

This page collects size-specific guidance that doesn’t belong on the parent Ship page.

The five sizes

Class	Typical examples	Boardable	Common purposes
`ship_xs`	Drones, mining drones, combat drones	No	Auxiliary (carried by larger ships)
`ship_s`	Fighters, scouts, interceptors	Via signalleak	Fight, scout
`ship_m`	Corvettes, miners, transports	Via signalleak	Fight, mine, trade, salvage
`ship_l`	Destroyers, freighters, builders	Via marines	Fight, trade, build, salvage
`ship_xl`	Carriers, resupplier, builders	Via marines	Fight, auxiliary, build

Filtering by class

<find_ship_by_true_owner name="$DestroyersAndCarriers"
    space="player.galaxy"
    faction="$Faction"
    class="[class.ship_l, class.ship_xl]"
    multiple="true"/>

class= accepts a single class OR a list of classes. Multi-class filter matches any.

Single-size

<find_ship_by_true_owner name="$Miners"
    space="$Sector"
    faction="$Faction"
    class="class.ship_m"
    primarypurpose="purpose.mine"
    multiple="true"/>

Combine class= and primarypurpose= for narrow matches (“M-class miners”).

Reading a ship’s size

<do_if value="$ship.class == class.ship_l">
    <!-- a destroyer / large ship -->
</do_if>

<do_if value="$ship.isclass.[class.ship_l, class.ship_xl]">
    <!-- a capital ship (L or XL) -->
</do_if>

$ship.iscapitalship is a vanilla shortcut for “ship_l OR ship_xl”:

<do_if value="$ship.iscapitalship">
    <!-- equivalent to the .isclass.[ship_l, ship_xl] check -->
</do_if>

Use .iscapitalship when you want clarity; use the list form when you need other size combinations.

Boarding capability

Size	Boardable by marines?	Notes
`ship_xs`	No	Drones are not boardable
`ship_s`	Via signal leak	Marines insert through signal leak instead of pods
`ship_m`	Via signal leak	Same as ship_s
`ship_l`	Via marines + pods	Standard boarding
`ship_xl`	Via marines + pods	Standard boarding (high resistance)

See Boarding for the full lifecycle.

Dock-size compatibility

Ships dock at docking bays of matching size:

Ship size	Required `docksize` tag
`ship_xs`	`tag.dock_xs`
`ship_s`	`tag.dock_s`
`ship_m`	`tag.dock_m`
`ship_l`	`tag.dock_l` or `pier_l`
`ship_xl`	`tag.dock_xl` or `pier_xl`

L and XL ships dock at piers (Pier) rather than ordinary dock areas.

<find_dockingbay name="$dock"
    object="$Station"
    checkoperational="true"
    docksize="tag.dock_l"
    multiple="false"/>

docksize= accepts a tag value. Engine matches ship size to compatible dock.

Build cost / time scaling

Vanilla scales build cost and time across sizes:

Class	Relative build cost	Relative build time
`ship_xs`	1×	1×
`ship_s`	~10×	~3×
`ship_m`	~50×	~10×
`ship_l`	~500×	~30×
`ship_xl`	~5000×	~120×

These are approximate — actual numbers depend on the specific ship macro. Modders adding new ships should follow vanilla’s scale to avoid economic imbalance.

Common gotchas

⚠ class.ship matches ALL sizes. $obj.isclass.ship is true for all of xs/s/m/l/xl. For specific size, use .isclass.ship_l etc.
⚠ ship_xs (drones) are NOT free agents. They’re carried inside larger ships. find_object may not return them at top-level; query the carrier’s .units.
⚠ Build cost across sizes is steep. A ship_xl costs 5000× a ship_xs. Mods adjusting costs should consider economic ripple effects.
⚠ Boardable threshold is at ship_l. Don’t expect a player to board your custom ship_m via marines — they’ll need a signal leak.
⚠ Lasertower is class.ship despite looking deployable. See Lasertower.

Cross-references

Ship — parent datatype (all sizes share)
Spacesuit — special ship_xs subtype
Lasertower — class.ship variant
Pier — L/XL docking
Dockingbay — dock structure
Boarding — size-dependent boarding mechanic