Baseboard is measured in linear feet, not square feet: add up the perimeter of each room, subtract the door openings, and add 10 to 15 percent for miscuts and corners. A 12 x 12 room with one doorway comes to about 50 linear feet with waste included.
Here is the method, the counts by room and by house size, and the openings that people forget to subtract.
Baseboard by room size
Each row is the perimeter, minus one 3 ft doorway, plus 10 percent waste:
| Room | Perimeter | Minus one doorway | Order |
|---|---|---|---|
| 10 x 10 ft | 40 ft | 37 ft | 41 ft |
| 12 x 12 ft | 48 ft | 45 ft | 50 ft |
| 12 x 15 ft | 54 ft | 51 ft | 57 ft |
| 15 x 20 ft | 70 ft | 67 ft | 74 ft |
The baseboard calculator runs your exact dimensions, and it works in the stock lengths suppliers actually sell rather than raw linear feet, which changes what you buy.
Baseboard for a whole house
For budgeting before you have measured every room, residential layouts land at roughly 0.21 to 0.26 linear feet of baseboard per square foot of floor area. The range is wide because it depends entirely on how the space is divided: several small bedrooms produce far more wall perimeter than one large open plan of the same area.
| House size | Approximate baseboard |
|---|---|
| 1,000 sq ft | 210 to 260 ft |
| 1,500 sq ft | 320 to 390 ft |
| 2,000 sq ft | 420 to 520 ft |
| 2,500 sq ft | 530 to 650 ft |
Treat these as a planning figure only. Once you are ordering, measure room by room, because a house at the top of that range and one at the bottom differ by a hundred feet of trim.
What to subtract, and what not to
Subtract cased openings and doorways, since baseboard stops at the casing on both sides. A standard interior door consumes about 3 feet of run, a double door or a cased opening 5 to 6.
Subtract the run behind full-height cabinetry and built-ins, kitchen base cabinets, a fitted wardrobe, a bookcase that reaches the floor. Baseboard does not run behind them.
Do not subtract windows. Baseboard passes underneath them unless the window is floor-to-ceiling. This is the most common measuring error, and it leaves you short.
Do not subtract radiators, furniture, or appliances that sit against a wall. The trim runs behind them, and stopping it short shows the moment anything is moved.
Add for a fireplace surround or a hearth that projects into the room, since the trim wraps around it rather than running straight past.
Why the waste factor is not optional
Ten percent is the working minimum and 15 percent is safer on a first job. Three things consume it:
- Outside corners need a miter on both pieces, and getting a tight one usually means cutting slightly long and trimming back, sometimes twice.
- Coped inside corners occasionally split at the thin edge of the profile and have to be recut.
- Stock lengths rarely match wall lengths. A 13 ft wall cut from a 14 ft board leaves a foot of offcut that is too short to use anywhere else, and that waste is real even though the arithmetic says otherwise.
Buying a little extra also protects against the supplier changing profiles between production runs, which makes matching a single replacement piece months later surprisingly difficult.
Finishing a room? The drywall calculator sizes the board that goes up first, and the paint calculator covers the walls the trim runs along.