Baseboard and trim calculator
Enter the room size and doorways. Works for baseboard and, if you set doors to zero, crown molding.
Trim needed
45 linear feet
- Pieces to buy
- 4 16 ft pieces
- Room perimeter
- 48 ft
How it works
Baseboard runs around the room’s perimeter, 2 × (length + width), minus the width of each doorway. The calculator adds a cut allowance and divides by your piece length.
The piece count assumes you can use offcuts on short walls. If every wall needs its own pieces, lay out each wall separately, since a 12 ft wall can’t be done with one 8 ft board.
Example
With room length 12 ft, room width 12 ft, doorways 1, doorway width 36 in, piece length: 16 ft, extra for cuts 10%, the answer is 45 linear feet.
Tips before you buy
- Longer pieces mean fewer joints on long walls. Use 16 ft boards where you can.
- Corners take extra material, especially for crown molding with its angled cuts. Use 15% or more for rooms with lots of corners.
- Let wood trim sit in the room for a couple of days before installing so it adjusts to the humidity.
Common questions
How much baseboard for a 12×12 room?
48 feet of perimeter minus one 3 ft doorway is 45 linear feet. That’s four 16 ft pieces with 10% extra.
How do I measure for baseboard?
Measure each wall at floor level, add them up, and subtract doorways. Closets count if you’re trimming them.
Do I subtract doors for crown molding?
No. Crown runs the full perimeter at the ceiling, so set doorways to 0.