Citra: Best config.ini for 3DS Resolution Scaling

The objective is to maximize the Resolution Factor while using Bicubic Filtering to smooth out the transition between low-res source textures and high-res rendered geometry.

1. Locating the Configuration File

Depending on your platform, the file is located here:

• Windows: %AppData%\Citra\config\config.ini
• Android: Documents/citra-emu/config/config.ini

2. The “4K Ultra” Config Fragment

Open your config.ini and locate the [Renderer] section. For a 4K display, you want to set the factor to at least 9 or 10, but ensure the following flags are synchronized:

Parameter	Recommended Value	Technical Purpose
graphics_api	1 (Vulkan)	Lowest driver overhead; essential for high resolution scaling.
resolution_factor	9 (for 4K)	Sets the internal resolution to ~2160p ($9 \times 240p$).
texture_filter	2 (Bicubic)	Smooths textures without the “oil painting” look of xBRZ.
use_hw_shader	true	Required for GPU-side scaling; disabling this will crush your CPU.
use_accurate_mul	false	Disable for performance unless you see “Vertex Explosions.”

3. Fixing the “Internal Resolution Hack” (Android)

In 2026, some mobile chipsets (Snapdragon 8 Gen 4+) can actually handle $4 \times$ resolution but struggle with Citra’s default UI caps.

• The Hack: In your config.ini, look for resolution_factor. On mid-range devices, setting this to 200 (a specific flag for some forks) forces the GPU to ignore standard caps, potentially gaining 5-10 FPS by bypassing the standard resolution-stepping logic ($R_{logic}$).

4. Technical Synergy: Post-Processing Shaders

Resolution scaling fixes the geometry (lines), but not the textures. To make 3DS games look truly modern at 4K:

1. Set pp_shader_name in your config.ini to Anime4K or AMD_FSR.
2. Enable “Stereoscopic 3D” if you are using a VR headset or a 3D-capable display; Citra’s upscaler correctly maps depth at high resolutions, making the 3D effect sharper than on the original hardware.