diff --git a/src/engine/objects/Warehouse.java b/src/engine/objects/Warehouse.java
index adcd6b9d..39d2c064 100644
--- a/src/engine/objects/Warehouse.java
+++ b/src/engine/objects/Warehouse.java
@@ -25,6 +25,7 @@ import org.pmw.tinylog.Logger;
 import java.sql.SQLException;
 import java.util.ArrayList;
 import java.util.EnumSet;
+import java.util.HashMap;
 import java.util.concurrent.ConcurrentHashMap;
 
 public class Warehouse {
@@ -68,6 +69,20 @@ public class Warehouse {
 
     }
 
+    public static HashMap<Enum.ResourceType, Integer> calculateWarehouseOverdraft(Warehouse warehouse, HashMap<Enum.ResourceType, Integer> costMap) {
+        HashMap<Enum.ResourceType, Integer> overdraft = new HashMap<>();
+
+        for (Enum.ResourceType resourceType : costMap.keySet()) {
+
+            int cost = costMap.get(resourceType);
+
+            if (cost > warehouse.resources.get(resourceType))
+                overdraft.put(resourceType, cost - warehouse.resources.get(resourceType));
+        }
+
+        return overdraft;
+    }
+
     public static void warehouseDeposit(MerchantMsg msg, PlayerCharacter player, NPC npc) {
 
         Building warehouseBuilding;