Baked vs Realtime Lighting
Precomputed or calculated every frame
Also known as: Baked lighting · Realtime lighting · Mixed lighting · Unity light mode · Static lighting
Definition
Baked lighting is calculated ahead of time and stored in lightmaps and probes, while realtime lighting is calculated every frame. Baked light is cheap to run and can include soft bounced light, but it cannot move or change. Realtime light reacts to moving objects and changes of day and night, but costs performance. Mixed lighting combines the two, with baked indirect light and some realtime direct light and shadows. Unity sets this per light with the Light Mode.
In production
Bake what never moves, such as sun, ambient light and interior lamps, and keep realtime for lights that must move or switch. Mobile and VR projects lean heavily on baking for performance, while modern desktop engines such as Unreal's Lumen can do much of this in real time. Baked scenes need clean lightmap UVs and sensible lightmap resolution, and light probes for moving objects.
Tools that use Baked vs Realtime Lighting
See also
Lightmap
Pre-baked indirect lighting
Light Probe
Baked light sampled for moving objects
Global Illumination
Light bouncing between surfaces
Lumen
UE5 dynamic global illumination
Lightmaps Look Wrong in Unity
Black, dark or blotchy baked lighting
Light Types
Directional, point, spot and area lights
Mobile Optimization
Art budgets for phones and tablets
VR Performance Budget
Why VR needs higher frame rates and simpler art