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Flooring & TileBaseboard Calculator — How Much Trim Do I Need?
Enter the room’s length and width to estimate baseboard or trim — the perimeter plus 10% for miter cuts, and how many 8-foot pieces to buy.
How this calculator works
We figure the room perimeter — 2 × (length + width) — add 10% for miter cuts and waste, and divide by 8 ft to count standard pieces. The same approach works for crown molding and shoe molding.
What changes how much you need
- Subtract about 3 ft for each doorway if your room has several.
- Mitered corners waste material — 10% is a safe allowance.
- Trim comes in 8, 12, and 16-ft lengths; longer pieces mean fewer seams on long walls.
- Buy one or two extra pieces for mistakes and future repairs.
Baseboard needed by room size (perimeter + 10%)
Before subtracting doorways. Knock off about 3 ft per doorway if the room has several.
| Room size | Perimeter | Linear ft to buy | 8-ft pieces |
|---|---|---|---|
| 10 × 10 ft | 40 ft | 44 ft | 6 |
| 12 × 12 ft | 48 ft | 53 ft | 7 |
| 12 × 14 ft | 52 ft | 57 ft | 8 |
| 14 × 16 ft | 60 ft | 66 ft | 9 |
| 16 × 20 ft | 72 ft | 79 ft | 10 |
| 20 × 24 ft | 88 ft | 97 ft | 13 |
Pieces to buy by stock length
Longer stock means fewer seams on a long wall, but more offcut waste in a small room — and 16-ft trim is awkward to transport.
| Linear ft needed | 8-ft pieces | 12-ft pieces | 16-ft pieces |
|---|---|---|---|
| 44 ft | 6 | 4 | 3 |
| 53 ft | 7 | 5 | 4 |
| 66 ft | 9 | 6 | 5 |
| 79 ft | 10 | 7 | 5 |
| 97 ft | 13 | 9 | 7 |
Frequently asked questions
How much baseboard do I need for a room?
Add up the perimeter (2 × length + 2 × width), subtract doorways, and add about 10% for cuts. A 14×12 ft room needs roughly 57 linear feet.
How many linear feet of baseboard for a 12×12 room?
A 12×12 ft room has a 48-foot perimeter, so about 53 linear feet with a 10% allowance for miter cuts — seven 8-ft pieces, or five 12-ft pieces.
How long are baseboard pieces?
Commonly 8, 12, or 16 feet. This calculator counts 8-ft pieces; the table above converts the same linear footage into 12-ft and 16-ft stock.
Do I subtract doorways from the baseboard measurement?
Yes. A standard interior doorway is about 3 feet wide, and cased openings can be much wider. Subtract each one from the perimeter before adding the waste allowance — in a room with three doorways that is roughly 9 feet, most of a whole piece.
How much extra should I buy?
About 10% over the perimeter for miter cuts, plus a spare piece or two.
Is crown molding measured the same way?
The linear footage is the same perimeter calculation, but crown needs a bigger waste allowance — 15% rather than 10% — because compound miters at the corners are less forgiving and a botched cut wastes more of the piece.
Do I need to calculate shoe molding separately?
Shoe molding and quarter round run the same perimeter as the baseboard they sit against, so the linear footage is identical. Order them together and the waste allowance covers both.