HDRI to Unity skybox

The short answer

Unity reads an equirectangular HDRI (a 2:1 latitude-longitude panorama) directly, so the usual method does not use individual cube faces: import the .hdr or .exr, put it on a material, and assign that material as the scene's skybox. There are three ways to build that material. The Skybox/Panoramic shader samples the flat panorama at render time. The cube texture shape has Unity reproject the same file into a cubemap (six square faces) at import. The legacy Skybox/6 Sided shader takes six separate images; this is the one method that needs a converter like this tool. Whichever material you build, assign it in Lighting > Environment > Skybox Material.

Method 1: Skybox/Panoramic material

This method has the fewest steps: the panorama stays a plain 2D texture and the shader does the spherical math per pixel.

1. Drag the .hdr or .exr into the Project window. Leave the texture shape at 2D.
2. Create a material (Assets > Create > Material) and switch its shader to Skybox > Panoramic.
3. Assign the texture to Spherical (HDR). Keep Mapping on Latitude Longitude Layout and Image Type on 360 Degrees.
4. Open Window > Rendering > Lighting, switch to the Environment tab, and set Skybox Material to your new material.

The material's Rotation slider spins the sky around the vertical axis, and Exposure trims its brightness without changing the source file.

Method 2: a cube texture

This method uses the same input file with a different import setting: Unity converts the panorama to a cubemap asset at import, and the GPU samples that cubemap at runtime.

1. Select the imported texture. In the Inspector, set Texture Shape to Cube.
2. Set Mapping to Latitude-Longitude Layout (Cylindrical), or leave Auto, which detects the 2:1 panorama. Then Apply.
3. Create a material with the Skybox > Cubemap shader and assign the cube texture to it.
4. Assign the material in the Lighting window as before.

Prefer this method over the panoramic shader when you want cubemap compression (BC6H keeps the HDR range at a quarter of the memory), cheaper sampling on weak GPUs, or a cubemap asset that other systems, such as a custom shader or a fallback reflection, can sample directly.

Method 3: the six-sided skybox

The Skybox/6 Sidedshader predates both methods above and takes six separate textures, one per cube face. Unity marks it as legacy, but it still ships, and some pipelines (skyboxes authored per face, ports from older engines) provide the sky as six images. The converter's six labeled faces go into these slots.

Match by the bracketed axis: Unity's six-sided slots are labeled from the skybox's point of view, so its Left [+X] slot takes the face the converter calls Right (+X), and vice versa. If a seam (the edge where two cube faces meet) looks mirrored, swap the two side pairs first; six-sided conventions are the least standardized part of skybox work.

Lighting and reflections from the skybox

Assigning the skybox material only sets the visible sky; the same image can also light the scene. In the Lighting window's Environment tab, set Environment Lighting > Source to Skybox. The HDRI's color and intensity then drive the ambient light. Environment Reflections defaults to the skybox too, so glossy materials reflect the sky without any reflection probes placed.

Interiors and grounded objects still need local Reflection Probes, which capture the skybox plus the scene around them. After changing the skybox, regenerate lighting (or let auto-generate run) so baked GI and the ambient probe use the new sky.

HDR import pitfalls

• Max Size defaults to 2048, which downscales a 4K panorama without warning. If the sky looks soft, raise it to the source resolution.
• Keep HDR sources in HDR containers. A .hdr or .exr import stays linear float and survives into BC6H; a tone-mapped .png clamps the sun to 1.0, so the lighting becomes flat.
• sRGB (Color Texture) does not apply to float formats, but if you use an 8-bit skybox, leave sRGB on so Unity does not darken it twice.
• Set exposure in one place: the material's Exposure slider or your tonemapping post stack. If you set both, the sky no longer matches the lighting it casts.

For the input each other engine wants, see Cubemap or equirectangular? If your panorama starts as a Blender render, the Blender guide covers exporting the equirectangular HDR that this page starts from.