# CBV, IBV and VBV byte alignment

The CBV (constant buffer view) SizeInBytes is required to be 256-byte aligned.

Should the associated ID3D12Resource have a Width (i.e. D3D12_RESOURCE_DESC) equal to/greater than that same size or may it be smaller, as the additional padding of the CBV won't be accessed/used in the shaders anyway? For example, is it allowed to create a CBV with SizeInBytes equal to 256 bytes for a ID3D12Resource with Width equal to 64 bytes?

Are there constraints for the IBV (index buffer view) and VBV (vertex buffer view) SizeInBytes as well?