I have a 125 amp meter panel and want to run a 100 amp service to a panel in my shop. The distance is approx 50 feet. What size conductors are required?
Thanks, dave

As a minimum , use 3 - #2 Alum XHHW insulation and 1 - #4 Al XHHW as equipment ground in 1-1/4" conduit, complete with elbows , fittings, and connectors from panel to panel.

Technically, need to use a 90 Amp circuit breaker. Many inspectors allow a 100 amp breaker used.

I'm only thinking of using copper!!

I'm only considering copper

I agree with TK. To add: Although 50 feet is not that far, it "may be” possible to need more than four bends to complete your conduit run. Per code:There shall not be more than the equivalent of four quarter bends (360 degrees total) between pull points. An example of a pull point would be and electrical box.

Then 3- # 3 and 1- #8 copper THHN/THWN.