diff --git a/src/gl/renderer/gl_renderer.cpp b/src/gl/renderer/gl_renderer.cpp
index bac55edb8..3e839ed4c 100644
--- a/src/gl/renderer/gl_renderer.cpp
+++ b/src/gl/renderer/gl_renderer.cpp
@@ -74,6 +74,7 @@
 #include "gl/dynlights/gl_lightbuffer.h"
 
 EXTERN_CVAR(Int, screenblocks)
+EXTERN_CVAR(Int, vid_scalemode)
 
 CVAR(Bool, gl_scale_viewport, true, CVAR_ARCHIVE);
 
@@ -300,7 +301,7 @@ void FGLRenderer::SetOutputViewport(GL_IRECT *bounds)
 	mSceneViewport.height = height;
 
 	// Scale viewports to fit letterbox
-	if ((gl_scale_viewport && !framebuffer->IsFullscreen()) || !FGLRenderBuffers::IsEnabled())
+	if ((gl_scale_viewport && !framebuffer->IsFullscreen() && vid_scalemode == 0) || !FGLRenderBuffers::IsEnabled())
 	{
 		mScreenViewport.width = mOutputLetterbox.width;
 		mScreenViewport.height = mOutputLetterbox.height;
diff --git a/src/gl/system/gl_framebuffer.cpp b/src/gl/system/gl_framebuffer.cpp
index a684f4c4c..ba08acaf2 100644
--- a/src/gl/system/gl_framebuffer.cpp
+++ b/src/gl/system/gl_framebuffer.cpp
@@ -55,6 +55,7 @@
 EXTERN_CVAR (Float, vid_brightness)
 EXTERN_CVAR (Float, vid_contrast)
 EXTERN_CVAR (Bool, vid_vsync)
+EXTERN_CVAR(Int, vid_scalemode)
 
 CVAR(Bool, gl_aalines, false, CVAR_ARCHIVE)
 
@@ -63,6 +64,8 @@ FGLRenderer *GLRenderer;
 void gl_LoadExtensions();
 void gl_PrintStartupLog();
 void gl_SetupMenu();
+int ViewportScaledWidth(int width);
+int ViewportScaledHeight(int height);
 
 CUSTOM_CVAR(Int, vid_hwgamma, 2, CVAR_ARCHIVE | CVAR_GLOBALCONFIG | CVAR_NOINITCALL)
 {
@@ -180,18 +183,15 @@ void OpenGLFrameBuffer::Update()
 	Unlock();
 	CheckBench();
 
-	if (!IsFullscreen())
+	int clientWidth = ViewportScaledWidth(IsFullscreen() ? VideoWidth : GetClientWidth());
+	int clientHeight = ViewportScaledHeight(IsFullscreen() ? VideoHeight : GetClientHeight());
+	if (clientWidth > 0 && clientHeight > 0 && (Width != clientWidth || Height != clientHeight))
 	{
-		int clientWidth = GetClientWidth();
-		int clientHeight = GetClientHeight();
-		if (clientWidth > 0 && clientHeight > 0 && (Width != clientWidth || Height != clientHeight))
-		{
-			// Do not call Resize here because it's only for software canvases
-			Pitch = Width = clientWidth;
-			Height = clientHeight;
-			V_OutputResized(Width, Height);
-			GLRenderer->mVBO->OutputResized(Width, Height);
-		}
+		// Do not call Resize here because it's only for software canvases
+		Pitch = Width = clientWidth;
+		Height = clientHeight;
+		V_OutputResized(Width, Height);
+		GLRenderer->mVBO->OutputResized(Width, Height);
 	}
 
 	GLRenderer->SetOutputViewport(nullptr);
diff --git a/src/menu/videomenu.cpp b/src/menu/videomenu.cpp
index 5f139f0af..cc2f72fa6 100644
--- a/src/menu/videomenu.cpp
+++ b/src/menu/videomenu.cpp
@@ -123,6 +123,37 @@ CUSTOM_CVAR (Bool, vid_tft, true, CVAR_ARCHIVE|CVAR_GLOBALCONFIG)
 	}	
 }
 
+CUSTOM_CVAR (Int, vid_scalemode, 0, CVAR_ARCHIVE|CVAR_GLOBALCONFIG)
+{
+	if (self < 0 || self > 3)
+	{
+		self = 0;
+	}
+}
+
+int ViewportScaledWidth(int width)
+{
+	switch (vid_scalemode)
+	{
+	default:
+	case 0: return width;
+	case 1: return 320;
+	case 2: return 640;
+	case 3: return (int)roundf(width * 0.5f);
+	}
+}
+
+int ViewportScaledHeight(int height)
+{
+	switch (vid_scalemode)
+	{
+	default:
+	case 0: return height;
+	case 1: return 200;
+	case 2: return 400;
+	case 3: return (int)roundf(height * 0.5f);
+	}
+}
 
 //=============================================================================
 //
diff --git a/src/posix/cocoa/i_video.mm b/src/posix/cocoa/i_video.mm
index d15a20737..ebfa45e3b 100644
--- a/src/posix/cocoa/i_video.mm
+++ b/src/posix/cocoa/i_video.mm
@@ -151,8 +151,8 @@ CUSTOM_CVAR(Bool, fullscreen, false, CVAR_ARCHIVE | CVAR_GLOBALCONFIG)
 {
 	extern int NewWidth, NewHeight, NewBits, DisplayBits;
 
-	NewWidth      = screen->GetWidth();
-	NewHeight     = screen->GetHeight();
+	NewWidth      = screen->VideoWidth;
+	NewHeight     = screen->VideoHeight;
 	NewBits       = DisplayBits;
 	setmodeneeded = true;
 }
diff --git a/src/posix/sdl/hardware.cpp b/src/posix/sdl/hardware.cpp
index 20ff59325..8e5c44cf4 100644
--- a/src/posix/sdl/hardware.cpp
+++ b/src/posix/sdl/hardware.cpp
@@ -334,8 +334,8 @@ CUSTOM_CVAR(Bool, swtruecolor, true, CVAR_ARCHIVE|CVAR_GLOBALCONFIG|CVAR_NOINITC
 
 CUSTOM_CVAR (Bool, fullscreen, false, CVAR_ARCHIVE|CVAR_GLOBALCONFIG)
 {
-	NewWidth = screen->GetWidth();
-	NewHeight = screen->GetHeight();
+	NewWidth = screen->VideoWidth;
+	NewHeight = screen->VideoHeight;
 	NewBits = DisplayBits;
 	setmodeneeded = true;
 }
@@ -349,8 +349,8 @@ CUSTOM_CVAR (Float, vid_winscale, 1.f, CVAR_ARCHIVE|CVAR_GLOBALCONFIG)
 	else if (Video)
 	{
 		Video->SetWindowedScale (self);
-		NewWidth = screen->GetWidth();
-		NewHeight = screen->GetHeight();
+		NewWidth = screen->VideoWidth;
+		NewHeight = screen->VideoHeight;
 		NewBits = DisplayBits;
 		setmodeneeded = true;
 	}
diff --git a/src/win32/hardware.cpp b/src/win32/hardware.cpp
index 599fe00a5..f27c318c4 100644
--- a/src/win32/hardware.cpp
+++ b/src/win32/hardware.cpp
@@ -434,8 +434,8 @@ CUSTOM_CVAR(Bool, swtruecolor, true, CVAR_ARCHIVE|CVAR_GLOBALCONFIG|CVAR_NOINITC
 
 CUSTOM_CVAR (Bool, fullscreen, false, CVAR_ARCHIVE|CVAR_GLOBALCONFIG|CVAR_NOINITCALL)
 {
-	NewWidth = screen->GetWidth();
-	NewHeight = screen->GetHeight();
+	NewWidth = screen->VideoWidth;
+	NewHeight = screen->VideoHeight;
 	NewBits = DisplayBits;
 	setmodeneeded = true;
 }
@@ -449,8 +449,8 @@ CUSTOM_CVAR (Float, vid_winscale, 1.f, CVAR_ARCHIVE|CVAR_GLOBALCONFIG)
 	else if (Video)
 	{
 		Video->SetWindowedScale (self);
-		NewWidth = screen->GetWidth();
-		NewHeight = screen->GetHeight();
+		NewWidth = screen->VideoWidth;
+		NewHeight = screen->VideoHeight;
 		NewBits = DisplayBits;
 		//setmodeneeded = true;	// This CVAR doesn't do anything and only causes problems!
 	}
diff --git a/src/win32/win32gliface.cpp b/src/win32/win32gliface.cpp
index 8071399db..77963a43b 100644
--- a/src/win32/win32gliface.cpp
+++ b/src/win32/win32gliface.cpp
@@ -1260,8 +1260,8 @@ void Win32GLFrameBuffer::NewRefreshRate ()
 	if (m_Fullscreen)
 	{
 		setmodeneeded = true;
-		NewWidth = screen->GetWidth();
-		NewHeight = screen->GetHeight();
+		NewWidth = screen->VideoWidth;
+		NewHeight = screen->VideoHeight;
 		NewBits = DisplayBits;
 	}
 }
diff --git a/wadsrc/static/language.enu b/wadsrc/static/language.enu
index 01d316c24..1edd84500 100644
--- a/wadsrc/static/language.enu
+++ b/wadsrc/static/language.enu
@@ -2191,6 +2191,7 @@ VIDMNU_HIDPI			= "Retina/HiDPI support";
 VIDMNU_ASPECTRATIO		= "Aspect ratio";
 VIDMNU_FORCEASPECT		= "Force aspect ratio";
 VIDMNU_5X4ASPECTRATIO	= "Enable 5:4 aspect ratio";
+VIDMNU_SCALEMODE		= "Resolution scale";
 VIDMNU_ENTERTEXT		= "Press ENTER to set mode";
 VIDMNU_TESTTEXT1		= "T to test mode for 5 seconds";
 VIDMNU_TESTTEXT2		= "Please wait 5 seconds...";
diff --git a/wadsrc/static/menudef.txt b/wadsrc/static/menudef.txt
index 148238c9c..f0840fef1 100644
--- a/wadsrc/static/menudef.txt
+++ b/wadsrc/static/menudef.txt
@@ -1849,6 +1849,13 @@ OptionValue RatiosTFT
 	6.0, "21:9"
 	 -1, "$OPTVAL_ALL"
 }
+OptionValue ScaleModes
+{
+	0, "$OPTVAL_OFF"
+	1, "320x200"
+	2, "640x400"
+	3, "0.5x"
+}
 
 OptionMenu VideoModeMenu protected
 {
@@ -1862,6 +1869,7 @@ OptionMenu VideoModeMenu protected
 	Option "$VIDMNU_ASPECTRATIO",		"menu_screenratios", "Ratios"
 	Option "$VIDMNU_FORCEASPECT",		"vid_aspect", "ForceRatios"
 	Option "$VIDMNU_5X4ASPECTRATIO",	"vid_tft", "YesNo"
+	Option "$VIDMNU_SCALEMODE",			"vid_scalemode", "ScaleModes"
 	StaticText " "
 	ScreenResolution "res_0"
 	ScreenResolution "res_1"