diff --git a/docs/changelog.txt b/docs/changelog.txt
index 6b641885a..7a7b29391 100644
--- a/docs/changelog.txt
+++ b/docs/changelog.txt
@@ -87,9 +87,11 @@ Template for new versions:
 - unavailable tools are no longer listed in the tag indices in the online docs
 
 ## API
+- added ``Items::getCapacity``, returns the capacity of an item as a container (reverse-engineered), needed for `combine`
 
 ## Lua
 - added ``GRAY`` color aliases for ``GREY`` colors
+- added ``dfhack.items.getCapacity`` to expose the new module API
 - ``utils.search_text``: text search routine (generalized from internal ``widgets.FilteredList`` logic)
 
 ## Removed
diff --git a/library/LuaApi.cpp b/library/LuaApi.cpp
index 5faec6d88..870c28697 100644
--- a/library/LuaApi.cpp
+++ b/library/LuaApi.cpp
@@ -2139,6 +2139,7 @@ static const LuaWrapper::FunctionReg dfhack_items_module[] = {
     WRAPM(Items, markForTrade),
     WRAPM(Items, isRouteVehicle),
     WRAPM(Items, isSquadEquipment),
+    WRAPM(Items, getCapacity),
     WRAPN(moveToGround, items_moveToGround),
     WRAPN(moveToContainer, items_moveToContainer),
     WRAPN(moveToInventory, items_moveToInventory),
diff --git a/library/include/modules/Items.h b/library/include/modules/Items.h
index 9daac1feb..05d0049cf 100644
--- a/library/include/modules/Items.h
+++ b/library/include/modules/Items.h
@@ -212,6 +212,8 @@ DFHACK_EXPORT bool isRequestedTradeGood(df::item *item, df::caravan_state *carav
 DFHACK_EXPORT bool isRouteVehicle(df::item *item);
 /// Checks whether the item is assigned to a squad
 DFHACK_EXPORT bool isSquadEquipment(df::item *item);
+/// Returns the item's capacity as a storage container
+DFHACK_EXPORT int32_t getCapacity(df::item* item);
 
 }
 }
diff --git a/library/modules/Items.cpp b/library/modules/Items.cpp
index 983921576..944334480 100644
--- a/library/modules/Items.cpp
+++ b/library/modules/Items.cpp
@@ -2283,3 +2283,45 @@ bool Items::isSquadEquipment(df::item *item)
     auto &vec = plotinfo->equipment.items_assigned[item->getType()];
     return binsearch_index(vec, item->id) >= 0;
 }
+
+// reverse engineered, code reference: 0x140953150 in 50.11-win64-steam
+// our name for this function: itemst::getCapacity
+// bay12 name for this function: not known
+
+int32_t Items::getCapacity(df::item* item)
+{
+    CHECK_NULL_POINTER(item);
+
+    switch (item->getType()) {
+    case df::enums::item_type::FLASK:
+    case df::enums::item_type::GOBLET:
+        return 180;
+    case df::enums::item_type::CAGE:
+    case df::enums::item_type::BARREL:
+    case df::enums::item_type::COFFIN:
+    case df::enums::item_type::BOX:
+    case df::enums::item_type::BAG:
+    case df::enums::item_type::BIN:
+    case df::enums::item_type::ARMORSTAND:
+    case df::enums::item_type::WEAPONRACK:
+    case df::enums::item_type::CABINET:
+        return 6000;
+    case df::enums::item_type::BUCKET:
+        return 600;
+    case df::enums::item_type::ANIMALTRAP:
+    case df::enums::item_type::BACKPACK:
+        return 3000;
+    case df::enums::item_type::QUIVER:
+        return 1200;
+    case df::enums::item_type::TOOL:
+        {
+            auto tool = virtual_cast<df::item_toolst>(item);
+            if (tool)
+                return tool->subtype->container_capacity;
+        }
+        // fall through
+    default:
+        ; // fall through to default exit
+    }
+    return 0;
+}