How it works
Perimeter = 2 × (length + width) for each room, added together, or the total perimeter you enter. Linear feet = perimeter − number of doors × door width.
Pieces = ceil(linear feet × (1 + waste ÷ 100) ÷ piece length − 1e-9). The 10% waste default is an editable planning choice. Each rectangular room has 4 inside corners; corners are not counted in perimeter mode.
Worked example
A 12 × 14 ft room: 2 × (12 + 14) = 52 ft. Minus one 3 ft door: 49 ft. With 10% waste: 53.9 ft.
With 8 ft pieces: 53.9 ÷ 8 = 6.7 → 7 pieces.
Tips and common mistakes
- Measure the walls where the baseboard runs, and subtract only openings with no baseboard, such as doorways.
- Use “Add another room” to total several rooms; they add up before rounding.
- Longer pieces mean fewer joints but can be harder to carry and fit. The result lists all three lengths.
- Outside corners, such as around a bump-out, are not counted automatically.
- Door widths larger than the perimeter are blocked.
Questions about this calculator
How do I figure out how much baseboard I need?
Measure the room's perimeter, 2 × (length + width). Subtract the width of each door opening and add waste. Then divide by the length of the pieces you'll buy and round up.
How much baseboard do I need for a 12x12 room?
The perimeter is 48 ft. Minus one 3 ft door, that is 45 ft, or 49.5 ft with 10% waste. That is 7 pieces of 8 ft, 5 pieces of 12 ft, or 4 pieces of 16 ft.
How much baseboard do I need for a 2,000 sq ft house?
Floor area alone can't tell you, because baseboard follows the walls, not the floor. Measure each room's perimeter, subtract the doors, and add the rooms together; the calculator lets you add several rooms.
Sources
Values marked with a link come from the linked source, which opens in a new tab. Unit conversions and our own defaults are listed separately. Every value the site uses is in the methodology source register.
Where the numbers come from 1
- Meters per international foot
- 0.3048 m/ft
- NIST, international foot conversion (opens in a new tab)nist.gov
Unit conversions and our defaults11
- Inside corners in a rectangular room
- 4 corners/room
- Geometry: a rectangle has four corners
- Centimeters per meter
- 100 cm/m
- Metric prefix definition: centi is one hundredth
- Inches per foot
- 12 in/ft
- Unit definition: one foot contains twelve inches
- Percent denominator
- 100 %
- Definition of percent: parts per hundred
- Baseboard calculator starting room
- 12, 14 ft length, ft width
- Owner worked example; editable starting measurements
- Baseboard calculator starting door
- 1, 3 doors, ft width
- Owner worked example; editable, not a standard door width
- Baseboard piece lengths offered
- 8, 12, 16 ft
- Owner specification; editable selection
- Baseboard calculator starting piece length
- 8 ft
- Owner worked example; editable selection
- Baseboard waste default
- 10 %
- Owner planning default; editable
- Rooms that can be added in one estimate
- 8 rooms
- Build choice: keeps the form manageable; run the tool again for more rooms
- Count rounding tolerance
- 1e-9 unitless
- Owner specification: ceil(x − 1e-9)