I am looking to find out how big the wire needs to be to carry the load. This will be a 100 amp service coming from a 200 amp main [ meter ] . It will need to travel 200 to 250 ft underground to a barn. If some one could help me that would be great thaxs)))

Due to the length, economics, and the availability of typical materials, I would use #4/0 aluminum 4 wire URD cable. This is a cable with 4 wires that are twisted, can be direct buried. At each end you may need to terminate in a junction box to splice and change over to #2 wire because the #4/0 is too large to fit into 100 amp breakers.

Bury the cable at least 24 inches, with 6 " sand above and below, use at least 2" PVC Sch 40 conduit to sleeve the cable if it runs under road ways, use warning tape 12 " below grade the entire length of the cable.

Use 2" PVC Sch 40 at the riser at both ends to protect the cable.

What size copper do I need for 100 amp panel 130' away? & also what size ground?

Use 3 - # 2 copper with either THHN/THWN or XHHW insulation, along with a # 6 copper green for the equipment ground.

If this is for a separate building, then there needs to be a ground rod grounding the equipment ground bar, keep the neutral separate and isolated from equipment ground.

macj... you MUST start your own thread or the answers here will be confusing to the OP or to you.