diff --git a/editor/project_manager.cpp b/editor/project_manager.cpp
index 9a82ec879d5..cde0c96bf4c 100644
--- a/editor/project_manager.cpp
+++ b/editor/project_manager.cpp
@@ -150,8 +150,8 @@ void ProjectManager::_build_icon_type_cache(Ref<Theme> p_theme) {
 // Main layout.
 
 void ProjectManager::_update_size_limits() {
-	const Size2 minimum_size = Size2(680, 450) * EDSCALE;
-	const Size2 default_size = Size2(1024, 600) * EDSCALE;
+	const Size2 minimum_size = Size2(720, 450) * EDSCALE;
+	const Size2 default_size = Size2(DEFAULT_WINDOW_WIDTH, DEFAULT_WINDOW_HEIGHT) * EDSCALE;
 
 	// Define a minimum window size to prevent UI elements from overlapping or being cut off.
 	Window *w = Object::cast_to<Window>(SceneTree::get_singleton()->get_root());
@@ -159,8 +159,12 @@ void ProjectManager::_update_size_limits() {
 		// Calling Window methods this early doesn't sync properties with DS.
 		w->set_min_size(minimum_size);
 		DisplayServer::get_singleton()->window_set_min_size(minimum_size);
-		w->set_size(default_size);
-		DisplayServer::get_singleton()->window_set_size(default_size);
+		if (DisplayServer::get_singleton()->window_get_size() == default_size) {
+			// Only set window size if it currently matches the default, which is defined in `main/main.cpp`.
+			// This allows CLI arguments to override the window size.
+			w->set_size(default_size);
+			DisplayServer::get_singleton()->window_set_size(default_size);
+		}
 	}
 
 	Rect2i screen_rect = DisplayServer::get_singleton()->screen_get_usable_rect(DisplayServer::get_singleton()->window_get_current_screen());
diff --git a/editor/project_manager.h b/editor/project_manager.h
index 1cb963a6500..8ae76475a39 100644
--- a/editor/project_manager.h
+++ b/editor/project_manager.h
@@ -250,6 +250,9 @@ protected:
 public:
 	static ProjectManager *get_singleton() { return singleton; }
 
+	static constexpr int DEFAULT_WINDOW_WIDTH = 1152;
+	static constexpr int DEFAULT_WINDOW_HEIGHT = 800;
+
 	// Project list.
 
 	bool is_initialized() const { return initialized; }
diff --git a/main/main.cpp b/main/main.cpp
index 07c319c088d..f3df10f2a94 100644
--- a/main/main.cpp
+++ b/main/main.cpp
@@ -2459,6 +2459,15 @@ Error Main::setup(const char *execpath, int argc, char *argv[], bool p_second_ph
 	OS::get_singleton()->set_current_rendering_driver_name(rendering_driver);
 	OS::get_singleton()->set_current_rendering_method(rendering_method);
 
+#ifdef TOOLS_ENABLED
+	if (!force_res && project_manager) {
+		// Ensure splash screen size matches the project manager window size
+		// (see `editor/project_manager.cpp` for defaults).
+		window_size.width = ProjectManager::DEFAULT_WINDOW_WIDTH;
+		window_size.height = ProjectManager::DEFAULT_WINDOW_HEIGHT;
+	}
+#endif
+
 	if (use_custom_res) {
 		if (!force_res) {
 			window_size.width = GLOBAL_GET("display/window/size/viewport_width");