diff --git a/frontend/src/tools/drawing/CapacityDisplayTool.ts b/frontend/src/tools/drawing/CapacityDisplayTool.ts
index 4f15400..a1808d2 100644
--- a/frontend/src/tools/drawing/CapacityDisplayTool.ts
+++ b/frontend/src/tools/drawing/CapacityDisplayTool.ts
@@ -2,9 +2,12 @@ import { Tool } from '../Tool';
 import { YjsDocument } from '../../crdt/YjsDocument';
 
 class CapacityDisplayTool extends Tool {
-  constructor(yjsDoc: YjsDocument) {
+  private onCapacityUpdate: (totalCapacity: number, selectedCapacity: number) => void;
+
+  constructor(yjsDoc: YjsDocument, onCapacityUpdate?: (totalCapacity: number, selectedCapacity: number) => void) {
     super(yjsDoc);
     this.name = 'CapacityDisplayTool';
+    this.onCapacityUpdate = onCapacityUpdate || (() => {});
   }
 
   onMouseDown(event: MouseEvent): void {
@@ -34,17 +37,29 @@ class CapacityDisplayTool extends Tool {
   // Calculate capacity for selected tables
   calculateSelectedCapacity(): number {
     // In a real implementation, this would get selected tables from the canvas
-    // and calculate the total capacity based on table type and size
-    // For now, we'll return a placeholder value
-    return 0;
+    // For now, we'll count all chair elements as selected capacity
+    const elements = this.yjsDoc.getElements();
+    let count = 0;
+    elements.forEach(element => {
+      if (element.type === 'chair') {
+        count++;
+      }
+    });
+    return count;
   }
 
   // Calculate capacity for entire drawing
   calculateTotalCapacity(): number {
-    // In a real implementation, this would iterate through all elements in the Yjs document
-    // and count chairs or calculate capacity based on tables
-    // For now, we'll return a placeholder value
-    return 0;
+    // Iterate through all elements in the Yjs document
+    // and count chairs
+    const elements = this.yjsDoc.getElements();
+    let count = 0;
+    elements.forEach(element => {
+      if (element.type === 'chair') {
+        count++;
+      }
+    });
+    return count;
   }
 
   // Display capacity information
@@ -52,14 +67,8 @@ class CapacityDisplayTool extends Tool {
     const totalCapacity = this.calculateTotalCapacity();
     const selectedCapacity = this.calculateSelectedCapacity();
     
-    // In a real implementation, this would update the UI to show capacity information
-    console.log(`Total capacity: ${totalCapacity} seats`);
-    if (selectedCapacity > 0) {
-      console.log(`Selected capacity: ${selectedCapacity} seats`);
-    }
-    
-    // In a real implementation, this would show a modal or update a panel in the UI
-    alert(`Total capacity: ${totalCapacity} seats${selectedCapacity > 0 ? `\nSelected capacity: ${selectedCapacity} seats` : ''}`);
+    // Update the UI through the callback
+    this.onCapacityUpdate(totalCapacity, selectedCapacity);
   }
 }