How far apart do wall outlets have to be (the 6/12 foot rule)?

No point along a wall may be more than 6 feet from a receptacle, which works out to outlets no more than 12 feet apart (IRC E3901.2).

In living rooms, bedrooms, dining rooms, dens and similar rooms, receptacles must be placed so that no point measured horizontally along the floor line of any wall is more than 6 feet from an outlet. On a continuous wall that ends up meaning receptacles are spaced no more than 12 feet apart.

Any wall space 2 feet or wider counts, including space that wraps around a corner. Wall sections broken up by doorways, fireplaces, or fixed cabinets are measured as separate wall spaces.

The goal is that a lamp or small appliance with a standard cord can reach an outlet anywhere along the wall without an extension cord.