Receptacle Spacing Calculator
Wall length to outlet count and spacing rule.
What it does
Lamp cords stretch only six feet before they drape across walkways or vanish behind furniture. Receptacle spacing rules put outlets where cords already want to go: every twelve feet with no point over six from one. Counting starts at the wall length.
The tool above divides unbroken wall feet by twelve, floors, and adds one, then prints the spacing rule beside the count. Doors, fireplaces, and fixed cabinets break runs into separate walls.
NEC dwelling outlet rules with electrical-safety guidance carry this 6/12 geometry plus tamper, GFCI, and AFCI clauses behind it. Floor outlets near walls count; long fixed glass does not.
Lay out per run, not per room. Window walls, halls, and open floors each play by their section, and heaters and workshops want dedicated circuits beyond spacing math.
How to use
- Enter unbroken wall length in feet.
- Read minimum receptacle count.
- Keep 12 ft max apart, 6 ft to points.
- Restart runs at doors and fireplaces.
- Pick types per room rules.
- Confirm special rooms separately.
Formula
- length
- Unbroken wall length in feet.
Length runs unbroken wall feet per NEC dwelling rules. Openings and fixed features restart runs; floor outlets near walls count. Types, heights, and special rooms follow separate clauses.
Worked example
Example: 30 ft wall
30 ft of living-room wall.
- Wall run is 30 ft long.
- Rule: floor(30 / 12) + 1 = 3 receptacles.
- Max apart is 12 ft, 6 ft to any point.
- Doors and fireplaces break runs.
- Place so no cord stretches past 6 ft.
Reference table
| Wall | Outlets | Note |
|---|---|---|
| 12 ft | 2 | Ends covered |
| 13 to 23 ft | 2 | One mid run |
| 24 to 35 ft | 3 | Even split |
| 36 to 47 ft | 4 | Plan circuits |
| 48 ft | 5 | Split long runs |
Limits
- Dwelling runs only. Openings break walls.
- Types, heights, and rooms need their clauses.
- Commercial rules differ entirely.
- Layout aid, not a permit drawing.
Common mistakes
- Measuring through doors and fireplaces.
- Counting fixed glass as wall.
- Forgetting floor outlets count.
- Skipping GFCI and AFCI types.
- Starving heaters on shared circuits.
Try it yourself
Quick checks. Answers sit tucked under each question.
Outlets for a 12 ft wall?
floor(12 / 12) + 1 = 2 receptacles at 12 ft max apart.
Outlets for a 48 ft wall?
floor(48 / 12) + 1 = 5 receptacles at 12 ft max apart.
Questions
How many outlets per wall?
At least one every 12 feet with no point over 6 feet from an outlet, the 6/12 rule. A 30-foot wall needs 3; a 12-foot wall needs 2.
What breaks a wall run?
Fixed glass, doors, and fireplaces break wall space; counters and fixed cabinets have their own clauses. Measure each unbroken run separately.
Do floor outlets count?
Floor receptacles within 18 inches of the wall count for the run. They save open floors and window walls where boxes cannot go.
Which outlet types go where?
Tamper-resistant everywhere in dwellings, GFCI where water or outdoors intrude, AFCI where bedrooms and living areas require. Spacing is only the start.
Does this cover every room?
Yes for dwelling units; garages, basements, hallways, and outdoors carry their own minimums in the same article. Commercial rules differ entirely.
What fails inspections most?
Backstabbed wires, missing clamps, and overloaded strips. Space right, terminate right, and give heaters their own circuits.