If you are looking for Information here the following hints might be of interest:
We have the following Benchmark report available. That was performed based on MS Dynamic 2012 R1 but in terms of the sizing results things remained the same so it is still valid.
Important note: The tests in the Benchmark Report were performed on “standard” solution without any branch or ISV solutions or other customizations which can have a big impact on performance!
Within the MS Dynamics Lifecycle Services (https://lcs.dynamics.com) there is a tool called Usage Profiler which can help you with sizing tasks. If you like please have a look here:
Also the following presentation from Informationsource portal can help you in terms of the sizing topic:
a) MS Dynamics AX 2012 Performance, Benchmarks, Features & Patterns:
b) MS Dynamics AX 2012: Solution Architecture:
c) MS Dynamics AX 2012: Solution Architecture Best Practise: