Hole size is outside diameter of US conduit sizes. 1/2" conduit and pipe size is 7/8" actual hole size, 3/4" conduit and pipe size is 1.115" actual hole size
Actual hole size for 1 inch conduit is 1.362"
A trade size hole for a 2-1/2" EMT conduit connector, the hole needs to be 2-7/8" in diameter. A 3" rigid conduit can also use this size hole without the lock nuts falling into the hole.
4 inch rigid conduit
It is easy to put a 2-inch long piece of conduit that is less than half an inch in any cross-sectional measure into a half-inch conduit.
The recommended conduit size for accommodating 6 gauge wire is 1 inch.
For new 200 amp services the conduit size should be 3 inch PVC.
The appropriate conduit size for accommodating 6/3 wire is typically 1 inch in diameter.
The recommended PVC conduit size for accommodating a 6-3 wire is 1 inch.
For accommodating 4/3 wire, a 1-inch conduit size should be used.
The recommended conduit size for accommodating 6/3 wire is typically 1 inch in diameter.
For 10/2 wire, a 3/4 inch conduit should be used.
For 12/2 wire, a 1/2 inch conduit should be used.