Doing fill calculations .
Copper & Alum same conductor size , Same insulation ,
Same OD ????
Yoopersup

I am not aware of any table that shows them being different unless we are talking about "compact conductors" and I have never seen that in copper.

I haven;t seen any charts that say they are different .
Only way to be sure I get is get manufacturers specs on both.
Thank you

As an inspector, I think we have done our due diligence if we just follow the tables in the back of the NEC. As in installer you have to understand if you up size the raceway or the box over the minimum, your job is easier. It will not be as hard to pull in the conductors and easier to put the box together. It is like wire bending space. I can tell someone what the minimum size is but I still do not actually have to bend that conductor to make that turn.

Always depends on which side the Fence your on with a project.
As four starters we have 6000 plus feet of 6 inch HDPE full of
HV cable for starters . I want it to Code (as Always) . Having pulled a lot of wire myself
I know what you mean. As Always I thank you & others on this Forum for your imputes.
Thank you
Yoopersup

Just as a side FYI, the LBs, LLs, LRs, etc have fill issues. As far as I know, there should not be any differences between Cu and Al conductors with the same insulation. As Greg mentioned, exclude the 'compact' ,

When I had 'tools', the pipe was upsized to make life easier.

Whenever I have a long or twisty run I call out for the conduit to be increased by a trade size.
Unless I end up with someone who spends a dollar to save a penny and skinnies down the conduit it always works out being the same installed price...or a bit less.