How it works
The formula
run = 2 × (length + width) − doors × 3 ft
buy = run × 1.1
pieces = buy ÷ piece length, rounded up
buy = run × 1.1
pieces = buy ÷ piece length, rounded up
Assumptions
- The room is a rectangle. An L-shaped room has the same perimeter as the rectangle around it, so enter its overall length and width.
- A standard interior door is about 3 ft wide with its casing, and baseboard stops at the casing.
- 10% extra covers miter cuts at the corners and offcuts too short to use: our rule of thumb, not a published figure. A room with many short walls, closets or bump-outs needs more.
- Typical price for 3-1/4 in primed MDF baseboard: about $0.85–$1.35 per linear foot (checked Oct 2026), cheapest in 12 ft packs. Wider and solid-wood profiles cost more, so type your price.
Worked example
A 12 × 14 ft bedroom with one door, 12 ft pieces
- Perimeter: 2 × (12 + 14) = 52 ft
- Less one door: 52 − 3 = 49 ft
- Plus 10%: 49 × 1.1 = 53.9 ft ÷ 12 → 5 pieces (7 if you buy 8 ft)
Pieces by room size
| Room | Doors | Linear ft (with 10%) | 12 ft pieces | 8 ft pieces |
|---|---|---|---|---|
| 10 × 10 ft | 1 | 40.7 | 4 | 6 |
| 12 × 12 ft | 1 | 49.5 | 5 | 7 |
| 12 × 14 ft | 1 | 53.9 | 5 | 7 |
| 14 × 16 ft | 2 | 59.4 | 5 | 8 |
| 20 × 24 ft | 3 | 86.9 | 8 | 11 |
Questions people ask
How do I measure for baseboard?
Measure the length of every wall at the floor, add them up, and take off the width of each door opening. Add about 10% for miter cuts and waste, then divide by the length of the pieces you'll buy.
How much baseboard for a 12 × 12 room?
48 ft of wall, less 3 ft for one door, is 45 ft; with 10% extra that's 49.5 ft, or 5 pieces of 12 ft.
Should I buy 8 ft or 12 ft baseboard?
Longer pieces cover most walls without a joint and usually cost less per foot. Buy 8 ft if that's all your car can carry, or for a room with many short walls.
Do I need baseboard inside closets?
Usually yes, if the closet floor matches the room. A closet adds its two side walls to the run (its back wall replaces the opening), so add the closet's depth to the room length: that adds twice the depth to the perimeter.