diff --git a/src/window/gui/Gui.cpp b/src/window/gui/Gui.cpp
index b972f6c03..769528fb3 100644
--- a/src/window/gui/Gui.cpp
+++ b/src/window/gui/Gui.cpp
@@ -384,13 +384,18 @@ void Gui::DrawMenu() {
     gfx_current_game_window_viewport.width = (int16_t)size.x;
     gfx_current_game_window_viewport.height = (int16_t)size.y;
 
+    if (CVarGetInteger("gAdvancedResolution.Enabled", 0)) {
+        ApplyResolutionChanges();
+    }
+
     switch (CVarGetInteger("gLowResMode", 0)) {
         case 1: { // N64 Mode
             gfx_current_dimensions.width = 320;
             gfx_current_dimensions.height = 240;
+            /*
             const int sw = size.y * 320 / 240;
             gfx_current_game_window_viewport.x += ((int)size.x - sw) / 2;
-            gfx_current_game_window_viewport.width = sw;
+            gfx_current_game_window_viewport.width = sw;*/
             break;
         }
         case 2: { // 240p Widescreen
@@ -459,14 +464,93 @@ void Gui::ImGuiWMNewFrame() {
     }
 }
 
+void Gui::ApplyResolutionChanges() {
+    ImVec2 size = ImGui::GetContentRegionAvail();
+
+    const float aspectRatioX = CVarGetFloat("gAdvancedResolution.AspectRatioX", 16.0f);
+    const float aspectRatioY = CVarGetFloat("gAdvancedResolution.AspectRatioY", 9.0f);
+    const uint32_t verticalPixelCount = CVarGetInteger("gAdvancedResolution.VerticalPixelCount", 480);
+    const bool verticalResolutionToggle = CVarGetInteger("gAdvancedResolution.VerticalResolutionToggle", 0);
+
+    const bool aspectRatioIsEnabled = (aspectRatioX > 0.0f) && (aspectRatioY > 0.0f);
+
+    const uint32_t minResolutionWidth = 320;
+    const uint32_t minResolutionHeight = 240;
+    const uint32_t maxResolutionWidth = 8096;  // the renderer's actual limit is 16384
+    const uint32_t maxResolutionHeight = 4320; // on either axis. if you have the VRAM for it.
+    uint32_t newWidth = gfx_current_dimensions.width;
+    uint32_t newHeight = gfx_current_dimensions.height;
+
+    if (verticalResolutionToggle) { // Use fixed vertical resolution
+        if (aspectRatioIsEnabled) {
+            newWidth = uint32_t(float(verticalPixelCount / aspectRatioY) * aspectRatioX);
+        } else {
+            newWidth = uint32_t(float(verticalPixelCount * size.x / size.y));
+        }
+        newHeight = verticalPixelCount;
+    } else { // Use the window's resolution
+        if (aspectRatioIsEnabled) {
+            if (((float)gfx_current_game_window_viewport.width / gfx_current_game_window_viewport.height) >
+                (aspectRatioX / aspectRatioY)) {
+                // when pillarboxed
+                newWidth = uint32_t(float(gfx_current_dimensions.height / aspectRatioY) * aspectRatioX);
+            } else { // when letterboxed
+                newHeight = uint32_t(float(gfx_current_dimensions.width / aspectRatioX) * aspectRatioY);
+            }
+        } // else, having both options turned off does nothing.
+    }
+    // clamp values to prevent renderer crash
+    if (newWidth < minResolutionWidth) {
+        newWidth = minResolutionWidth;
+    }
+    if (newHeight < minResolutionHeight) {
+        newHeight = minResolutionHeight;
+    }
+    if (newWidth > maxResolutionWidth) {
+        newWidth = maxResolutionWidth;
+    }
+    if (newHeight > maxResolutionHeight) {
+        newHeight = maxResolutionHeight;
+    }
+    // apply new dimensions
+    gfx_current_dimensions.width = newWidth;
+    gfx_current_dimensions.height = newHeight;
+    // centring the image is done in Gui::StartFrame().
+}
+
 void Gui::StartFrame() {
     const ImVec2 mainPos = ImGui::GetWindowPos();
     ImVec2 size = ImGui::GetContentRegionAvail();
     ImVec2 pos = ImVec2(0, 0);
-    if (CVarGetInteger("gLowResMode", 0) == 1) {
+    if (CVarGetInteger("gLowResMode", 0) == 1) { // N64 Mode takes priority
         const float sw = size.y * 320.0f / 240.0f;
         pos = ImVec2(size.x / 2 - sw / 2, 0);
         size = ImVec2(sw, size.y);
+    } else if (CVarGetInteger("gAdvancedResolution.Enabled", 0)) {
+        if (!CVarGetInteger("gAdvancedResolution.PixelPerfectMode", 0)) {
+            if (!CVarGetInteger("gAdvancedResolution.IgnoreAspectCorrection", 0)) {
+                float sWdth = size.y * gfx_current_dimensions.width / gfx_current_dimensions.height;
+                float sHght = size.x * gfx_current_dimensions.height / gfx_current_dimensions.width;
+                float sPosX = size.x / 2 - sWdth / 2;
+                float sPosY = size.y / 2 - sHght / 2;
+                if (sPosY < 0.0f) { // pillarbox
+                    sPosY = 0.0f;   // clamp y position
+                    sHght = size.y; // reset height
+                }
+                if (sPosX < 0.0f) { // letterbox
+                    sPosX = 0.0f;   // clamp x position
+                    sWdth = size.x; // reset width
+                }
+                pos = ImVec2(sPosX, sPosY);
+                size = ImVec2(sWdth, sHght);
+            }
+        } else { // in pixel perfect mode it's much easier
+            const int factor = CVarGetInteger("gAdvancedResolution.IntegerScaleFactor", 1);
+            float sPosX = size.x / 2 - (gfx_current_dimensions.width * factor) / 2;
+            float sPosY = size.y / 2 - (gfx_current_dimensions.height * factor) / 2;
+            pos = ImVec2(sPosX, sPosY);
+            size = ImVec2(float(gfx_current_dimensions.width) * factor, float(gfx_current_dimensions.height) * factor);
+        }
     }
     if (gfxFramebuffer) {
         ImGui::SetCursorPos(pos);
diff --git a/src/window/gui/Gui.h b/src/window/gui/Gui.h
index 2ffb6a05b..b163e9e43 100644
--- a/src/window/gui/Gui.h
+++ b/src/window/gui/Gui.h
@@ -90,6 +90,7 @@ class Gui {
     void ImGuiWMNewFrame();
     void ImGuiRenderDrawData(ImDrawData* data);
     ImTextureID GetTextureById(int32_t id);
+    void ApplyResolutionChanges();
 
   private:
     struct GuiTexture {