diff --git a/Telegram/SourceFiles/settings/settings_experimental.cpp b/Telegram/SourceFiles/settings/settings_experimental.cpp
index dfc85fb2c..3b9a5a069 100644
--- a/Telegram/SourceFiles/settings/settings_experimental.cpp
+++ b/Telegram/SourceFiles/settings/settings_experimental.cpp
@@ -26,6 +26,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "mainwindow.h"
 #include "media/player/media_player_instance.h"
 #include "webview/webview_embed.h"
+#include "window/main_window.h"
 #include "window/window_peer_menu.h"
 #include "window/window_session_controller.h"
 #include "window/window_controller.h"
@@ -155,6 +156,7 @@ void SetupExperimental(
 	addToggle(Window::Notifications::kOptionGNotification);
 	addToggle(Core::kOptionFreeType);
 	addToggle(Data::kOptionExternalVideoPlayer);
+	addToggle(Window::kOptionNewWindowsSizeAsFirst);
 }
 
 } // namespace
diff --git a/Telegram/SourceFiles/window/main_window.cpp b/Telegram/SourceFiles/window/main_window.cpp
index 7f4a78f81..d726deb20 100644
--- a/Telegram/SourceFiles/window/main_window.cpp
+++ b/Telegram/SourceFiles/window/main_window.cpp
@@ -72,7 +72,15 @@ using Core::WindowPosition;
 	return result;
 }
 
-} // namespace
+base::options::toggle OptionNewWindowsSizeAsFirst({
+	.id = kOptionNewWindowsSizeAsFirst,
+	.name = "Adjust size of new chat windows.",
+	.description = "Open new windows with a size of the main window.",
+});
+
+} // namespace.
+
+const char kOptionNewWindowsSizeAsFirst[] = "new-windows-size-as-first";
 
 const QImage &Logo() {
 	static const auto result = QImage(u":/gui/art/logo_256.png"_q);
@@ -616,8 +624,12 @@ WindowPosition MainWindow::nextInitialChildPosition(bool primary) {
 	const auto adjust = [&](int value) {
 		return primary ? value : (value * 3 / 4);
 	};
-	const auto width = adjust(st::windowDefaultWidth);
-	const auto height = adjust(st::windowDefaultHeight);
+	const auto width = OptionNewWindowsSizeAsFirst.value()
+		? Core::App().settings().windowPosition().w
+		: adjust(st::windowDefaultWidth);
+	const auto height = OptionNewWindowsSizeAsFirst.value()
+		? Core::App().settings().windowPosition().h
+		: adjust(st::windowDefaultHeight);
 	const auto skip = ChildSkip();
 	const auto delta = _lastChildIndex
 		? (_lastMyChildCreatePosition - position)
diff --git a/Telegram/SourceFiles/window/main_window.h b/Telegram/SourceFiles/window/main_window.h
index df552098e..774543271 100644
--- a/Telegram/SourceFiles/window/main_window.h
+++ b/Telegram/SourceFiles/window/main_window.h
@@ -54,6 +54,8 @@ struct CounterLayerArgs {
 	required<style::color> fg;
 };
 
+extern const char kOptionNewWindowsSizeAsFirst[];
+
 [[nodiscard]] QImage GenerateCounterLayer(CounterLayerArgs &&args);
 [[nodiscard]] QImage WithSmallCounter(QImage image, CounterLayerArgs &&args);