Use 16-bit precision in shaders

By default, GPUs use 32-bit precision. You can use 16-bit precision instead in GPU calculations, which has the following benefits on mobile platforms:

ShadersA program that runs on the GPU. More info
See in Glossary use less memory, bandwidth, and power.
Calculations are faster. Using fewer bits can improve how the GPU allocates registers.

Create a 16-bit variable

To use 16-bit precision in a shader, use half when you declare a scalar, a vector, or a matrix. For example:

half _Glossiness;
half4 _Color;
half4x4 _Matrix;

To use 16-bit precision in a texture sampler, add _half when you declare it. For example:

Texture2D<half4> _MainTex;

16-bit precision might not be enough for some shader calculations. This might cause visible errors such as color banding or stuttering geometry. To check for errors, run your project on a platform that supports half. If there are errors, use float instead.

A half variable is stored in buffers with a size and alignment of 32 bits.

Use 16-bit values on more platforms

By default, half has no effect on higher performance platforms in Unity, for example platforms that use MacOS. A half variable becomes a float, and the GPU uses 32-bit values for calculations.

To use 16-bit precision on more platforms, go to Edit > Project Settings > Player and set Shader Precision Model to Uniform. Unity then treats half in your HLSL code as the following:

min16float for scalars
float for texture samplers

When Unity compiles shaders, min16float becomes a platform data type that allows the GPU to use 16-bit precision for calculations if it supports them. For example:

If you use DirectX 11 or 12, the variable remains a min16float.
If you use OpenGL, the variable becomes mediump.
If you use Vulkan, the variable becomes a RelaxedPrecision float.
If you use Metal, the variable becomes a half, which has a size and alignment of 2 bytes instead of 4 bytes.

To override the Shader Precision Model setting for textures, add _half when you declare a texture sampler. For example Texture2D<half4> _MainTex.