Flat extension cords are for under rugs. Round ones are not.

Use a flat cord. Round cords create a noticeable lump under the rug—exactly the trip hazard you’re trying to avoid. Flat cords are designed to be low-profile and lay flush against the floor.

But a quick reality check: running any extension cord under a rug is not ideal from a safety standpoint. The cord can overheat because heat gets trapped, especially if the rug is thick or you have furniture on top. A flat cord reduces the lump but doesn’t eliminate the fire risk entirely.

If you absolutely have to do it, get a flat cord that’s rated for the load (don’t cheap out on gauge), and avoid covering it with anything heavy. Better yet, route the cord along the baseboard or use a floor cord cover instead.