With the current APIs Unity provides, it is difficult to determine exactly where the memory footprint for a mesh is coming from, especially during runtime. Get internal memory during runtime in release mode is not possible which leads to estimates which is difficult without knowing the correct format which depends on many different factors. During profiling it's possible, but you will always get the profiler overhead. e.g. via Profiler.GetRuntimeMemorySize (mesh);

For Meshes there is already a call used by the profiler Mesh::GetRuntimeMemorySize() which consists of 2 parts which only return related memory in dev mode, otherwise zero.

- Profiler.GetRuntimeMemorySize (mesh); Includes base memory footprint for C++ objects as well as the base class.
- SharedMeshRenderingData::GetRuntimeMemorySize() returns the index buffer size + the vertex streams included.

So in theory we can enable the second part during runtime as it doesn’t require the profiler. This requires additionally scripting bindings. See the attached diff for the implementation. This returns the size the mesh occupies via mesh.GetRuntimeMemorySize ().

TestStuff.cs tests the call against other API calls in

Debug.Log("GetRuntimeMemorySize: "+mf.mesh.GetRuntimeMemorySize ());

Build the test scene in non development mode to iOS/Android and test on device.