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Baseboard Trim Calculator

Computes the room perimeter, subtracts door and other openings, adds a cutting-waste allowance and converts the length of baseboard (skirting) into stock pieces to buy, with the inside and outside corner count for a rectangular room and an optional cost.

Room length (m or ft)Room length in metres or feet (see unit). Room width (m or ft)Room width in metres or feet. Length unit (optional)Unit of the length inputs (m or ft). Lengths are reported in both units. Doors (optional)Number of door openings without baseboard. Door width (m or ft) (optional)Width of each door opening; default 0.9 m (metric) or 3 ft (imperial). Other openings (m or ft) (optional)Total length of other gaps with no baseboard (built-in cabinets, fireplace, archways). Trim piece length (m or ft) (optional)Length of the stock pieces you will buy; default 3.66 m (metric, a 12 ft length) or 12 ft (imperial). Common lengths: 2.4, 3, 3.66, 4.2 m; 8, 12, 16 ft. Waste allowance (%) (optional)Extra material for cuts, breakage and offcuts, applied as a multiplier (1 + waste_percent/100). 10 % covers mitre cuts, scarf joints and damaged ends; use 15 % for rooms with many corners. Price per piece (optional)Optional price of one stock piece; enables total_cost.

When to use

You need to know how many lengths of baseboard, skirting board, shoe molding or quarter round to buy for a room.

Do not use when: You need the compound angles for crown molding (use crown-molding-miter) or the room is L-shaped: split it into rectangles and add one inside and one outside corner per notch.

Formula

perimeter = 2 × (room_length + room_width); net = perimeter − doors × door_width − other_openings_length; trim_length_needed = net × (1 + waste_percent/100); pieces_to_buy = ceil(trim_length_needed / trim_piece_length); total_cost = pieces × price_per_piece.

Plain perimeter take-off; the waste allowance covers 45° mitres at outside corners, coped inside corners and scarf joints on long walls (pieces at least as long as the longest wall avoid joints). Shoe molding or quarter round needs the same length again.

Inputs

Parameter	Type	Unit	Required	Description
`room_length`	number	m or ft	yes	Room length in metres or feet (see unit). Range: > 0, ≤ 1000
`room_width`	number	m or ft	yes	Room width in metres or feet. Range: > 0, ≤ 1000
`unit`	enum: m \| ft		default m	Unit of the length inputs (m or ft). Lengths are reported in both units.
`doors`	integer		default 1	Number of door openings without baseboard. Range: ≥ 0, ≤ 50
`door_width`	number	m or ft	no	Width of each door opening; default 0.9 m (metric) or 3 ft (imperial). Range: > 0, ≤ 10
`other_openings_length`	number	m or ft	default 0	Total length of other gaps with no baseboard (built-in cabinets, fireplace, archways). Range: ≥ 0, ≤ 1000
`trim_piece_length`	number	m or ft	no	Length of the stock pieces you will buy; default 3.66 m (metric, a 12 ft length) or 12 ft (imperial). Common lengths: 2.4, 3, 3.66, 4.2 m; 8, 12, 16 ft. Range: > 0, ≤ 20
`waste_percent`	number	%	default 10	Extra material for cuts, breakage and offcuts, applied as a multiplier (1 + waste_percent/100). 10 % covers mitre cuts, scarf joints and damaged ends; use 15 % for rooms with many corners. Range: ≥ 0, ≤ 50
`price_per_piece`	number		no	Optional price of one stock piece; enables total_cost. Range: ≥ 0

Outputs

Output	Type	Unit	Description
`perimeter_m`	number	m	2 × (room_length + room_width).
`perimeter_ft`	number	ft	Perimeter in feet.
`trim_length_needed_m`	number	m	(perimeter − doors × door_width − other_openings_length) × (1 + waste_percent/100).
`trim_length_needed_ft`	number	ft	Same length in feet.
`pieces_to_buy`	integer		ceil(trim_length_needed / trim_piece_length).
`inside_corners`	integer		4 for a rectangular room (cope or 45° inside mitre each).
`outside_corners`	integer		0 for a rectangular room (add 1 inside + 1 outside per notch of an L-shape).
`total_cost`	number		pieces_to_buy × price_per_piece; only when a price is given.

Example

5 m × 4 m room, one 0.9 m door, 3.66 m pieces, 10 % waste: {"room_length":5,"room_width":4,"unit":"m","doors":1,"door_width":0.9,"trim_piece_length":3.66,"waste_percent":10} → {"perimeter_m":18,"perimeter_ft":59.06,"trim_length_needed_m":18.81,"trim_length_needed_ft":61.71,"pieces_to_buy":6,"inside_corners":4,"outside_corners":0}

14 ft × 12 ft room, two 3 ft doors, 12 ft pieces at $15, 10 % waste: {"room_length":14,"room_width":12,"unit":"ft","doors":2,"waste_percent":10,"price_per_piece":15} → {"perimeter_ft":52,"perimeter_m":15.85,"trim_length_needed_ft":50.6,"trim_length_needed_m":15.42,"pieces_to_buy":5,"total_cost":75}

GET https://tttkmbb.com/api/v1/calculate/baseboard-trim?room_length=5&room_width=4&unit=m&doors=1&door_width=0.9&trim_piece_length=3.66&waste_percent=10

Machine access

API: GET https://tttkmbb.com/api/v1/calculate/baseboard-trim (query parameters) or POST with a JSON body {"inputs": {...}}
Schema: https://tttkmbb.com/api/v1/calculators/baseboard-trim · Markdown: https://tttkmbb.com/construction/baseboard-trim.md · JSON definition: https://tttkmbb.com/construction/baseboard-trim.json
MCP: server https://tttkmbb.com/mcp, tool run_calculator with calculator_id="baseboard-trim"
OpenAPI operationId: estimate_baseboard_trim
Freshness: static. Authentication: none. Rate limit: fair use (see rate limits).

Sources

Wikipedia – Baseboard (reference)
Wikipedia – Molding (decorative) (reference)

FAQ

Should I subtract the door openings?

Yes, baseboard stops at the door casing; each door removes its width (0.9 m / 3 ft typical). Windows do not matter because they are above the baseboard.

Which piece length should I buy?

Pieces longer than the longest wall avoid scarf joints: 4.2 m or 16 ft for a 4 m / 13 ft wall. Shorter pieces are cheaper to transport but each joint costs extra waste.

Related calculators

Crown Molding Miter Calculator — Saw angles for crown molding corners.
Paint Calculator — Paint for the walls above the baseboard.
Flooring Calculator — Floor covering the baseboard will sit on.