diff --git a/packages/dockview-core/src/dockview/dockviewComponent.ts b/packages/dockview-core/src/dockview/dockviewComponent.ts
index b06410090..517f7c8b1 100644
--- a/packages/dockview-core/src/dockview/dockviewComponent.ts
+++ b/packages/dockview-core/src/dockview/dockviewComponent.ts
@@ -1640,7 +1640,12 @@ export class DockviewComponent
             );
 
             const group = this.createGroup(options);
-            this.doAddGroup(group, relativeLocation);
+            const size =
+                this.getLocationOrientation(relativeLocation) ===
+                Orientation.VERTICAL
+                    ? options.initialHeight
+                    : options.initialWidth;
+            this.doAddGroup(group, relativeLocation, size);
             if (!options.skipSetActive) {
                 this.doSetGroupAndPanelActive(group);
             }
@@ -1654,6 +1659,13 @@ export class DockviewComponent
         }
     }
 
+    private getLocationOrientation(location: number[]) {
+        return location.length % 2 == 0 &&
+            this.gridview.orientation === Orientation.HORIZONTAL
+            ? Orientation.HORIZONTAL
+            : Orientation.VERTICAL;
+    }
+
     removeGroup(
         group: DockviewGroupPanel,
         options?:
diff --git a/packages/dockview-core/src/dockview/dockviewGroupPanelModel.ts b/packages/dockview-core/src/dockview/dockviewGroupPanelModel.ts
index ae3c07ae3..1d02d4d33 100644
--- a/packages/dockview-core/src/dockview/dockviewGroupPanelModel.ts
+++ b/packages/dockview-core/src/dockview/dockviewGroupPanelModel.ts
@@ -52,6 +52,8 @@ interface CoreGroupOptions {
     hideHeader?: boolean;
     skipSetActive?: boolean;
     constraints?: Partial<Contraints>;
+    initialWidth?: number;
+    initialHeight?: number;
 }
 
 export interface GroupOptions extends CoreGroupOptions {