How much baseboard you need
Baseboard length is the room perimeter minus door openings: 2 × (length + width) − total door width. A 12 × 10 ft room with 3 ft of doorways needs 41 linear feet. Buy in stock lengths that minimize joints.
Closets, alcoves and bay windows add to the run, so walk the room and measure every wall segment that will actually receive trim. The running length you need is simply the room's perimeter.
How to use this calculator
Enter room length, width, and the combined door width to skip. The result is linear feet. Painting the room too? The wall area feeds the paint calculator. While you are measuring, work out the floor area with the square footage calculator.
Cuts and waste
Add about 10–15% for miter cuts at corners and matching long walls from one board. Outside corners waste more. For a wider feature wall finish, see the drywall calculator.
Buy the longest stock lengths that fit your walls. A 12 ft wall finished with a single board has no seam to sand and fill, while two shorter pieces need a joint. When a wall is longer than the stock available, cut both pieces at 45 degrees so the joint overlaps rather than butting square, and place it away from the door you enter by. Measure each wall separately instead of trusting the room's nominal size, since out-of-square corners and drywall thickness often change a run by an inch or two.
Frequently asked questions
- How do I calculate baseboard?
- Add up the room perimeter, then subtract the width of door openings that have no baseboard.
- Do I subtract closets and doors?
- Subtract door openings; add closet interiors if you are trimming them too.
- How much extra baseboard should I buy?
- About 10–15% for miter cuts, corners and matching long runs from single boards.
- How is room perimeter calculated?
- Perimeter is 2 × (length + width) for a rectangular room.
- How do I turn linear feet into boards to buy?
- Divide your total linear feet by the stock length you can get, then round up. Buying 16 ft boards for a 41 ft room means three boards, and planning which wall each board covers keeps joints off the main sightlines.