Undertale
21:9
Unsupported
32:9
Unsupported
Gameplay Scaling
Fixed FOV crop
HUD
Centered
Centered HUD
Native
Cutscenes
16:9 pillarboxed
Menus
16:9
FOV
Correct
Black Bars
Full-time
Flawless Widescreen
Not Supported
Community Fix
Low benefit
Online Safety
Safe
Overview
Undertale renders a fixed 4:3 640x480 image, so on an ultrawide monitor it is shown with large black bars on both sides. PCGamingWiki marks ultrawide as unsupported; a hex edit only changes the output resolution and does not reveal more of the game.
Compatibility details
21:9 SupportUnsupported
32:9 SupportUnsupported
Gameplay ScalingFixed FOV crop
HUD BehaviorCentered
Centered HUDNative
Cutscene Support16:9 pillarboxed
Menu Support16:9
FOVCorrect
Black BarsFull-time
StretchingNone observed
Fixes
Ultrawide doesn't add much here.
Undertale is a fixed 4:3 (640x480) pixel-art game. Its rooms and battles are designed for that frame, so extra width would add nothing; it runs with side bars.
Patch history & verification
Current Steam build (number not confirmed)Oct 17, 2026
Verified PCGamingWiki: widescreen hackable via hex edit, ultrawidescreen false. No Flawless Widescreen module or other ultrawide fix found.