Baseboard Trim Calculator

How it works

Baseboard runs along the foot of every wall and stops at each doorway, so the length needed is the room's perimeter less the width of the doorways. For a rectangular room the perimeter is twice the length plus twice the width.

A waste allowance covers the offcuts at corners and joints. The default is 10%, the margin Family Handyman's baseboard guide (Carmen De La Paz, Sept. 10, 2025) adds for bad cuts; it is editable, and rooms with many inside and outside corners lose more to offcuts. The run with waste is divided by the stock length and rounded up to whole lengths.

Shoe molding or quarter round sits along the foot of the baseboard and follows the same run, so it takes the same number of lengths. The cost is for the whole lengths counted, at the price per foot entered.

Formula

perimeter     = 2 × (length + width)   (or as entered)
baseboard run = perimeter − doorways × width per doorway ÷ 12
with waste    = run × (1 + waste % ÷ 100)
lengths       = with waste ÷ stock length, rounded up
cost          = lengths × stock length × price per ft (+ shoe lengths × stock × shoe price)

Example

A 14 × 12 ft room has a 52 ft perimeter. Taking off one 36 in doorway leaves 49 ft of baseboard, or 53.9 ft with 10% waste.

In 16 ft lengths that is 53.9 ÷ 16 = 3.37, so 4 lengths, which at $1.50 a foot is 4 × 16 × $1.50 = $96.00.

Assumptions and limitations

• Lengths are pooled: offcuts from one wall are counted toward the next. A wall longer than the stock length needs a splice, and short pieces between doors and corners can leave offcuts too short to reuse, which the waste allowance must cover.
• Every doorway is taken off at the same width. Built-in cabinets, fireplace hearths and other places the baseboard stops are not taken off unless they are counted as doorways or left out of the perimeter.
• Shoe molding follows the baseboard run exactly; in practice it is sometimes left off behind furniture or doors.
• The 10% waste allowance and the prices are typical or illustrative values and are editable.

Frequently asked questions