Trim is sold in sticks, cut with angles, and wasted at every corner — this turns a room into the right number of boards.
Room details
ft
ft
Sticks to buy
—
Linear feet needed (incl. 10% waste)—
Room perimeter—
Wall runs to cover—
Buy sticks longer than your longest wall where possible — a 15-ft wall from one 16-ft stick has zero joints. Splices mid-wall are done with a scarf (angled) joint over a stud, not a butt joint.
Trim math is perimeter math
Baseboard need is the room perimeter minus door openings (about 3 ft each), plus 10% for the miters, coping, and the inevitable miscut. The real decision is stick length: fewer joints looks better and installs faster, so match sticks to walls.
linear ft = (2(L+W) − doors × 3) × 1.10 · sticks = ceil(linear ft ÷ stick length)
Worked example
A 15 × 12 room with one door: 54 ft perimeter − 3 = 51, with waste 57 linear ft — five 12-ft sticks. Buying 16-footers instead means the two long walls each run jointless, which is worth the awkward car ride. The same math covers crown molding, chair rail, and quarter-round; crown deserves 15% waste because its compound miters eat mistakes.
Corners: cope, don't just miter
Outside corners get mitered at 45°. Inside corners look better coped — one piece runs square into the corner and the mating piece is cut to its profile — because drywall corners are never a true 90° and coped joints don't open up when seasons change the wood.
Frequently asked questions
How do I calculate baseboard for a room?
Add all wall lengths (the perimeter), subtract about 3 feet per door opening, then add 10% for cuts and waste. Convert to sticks by dividing by the trim length you’ll buy.
What length of trim should I buy?
The longest sticks you can transport that meet or beat your longest walls — a jointless wall always looks better. 16-ft sticks cover most rooms’ long walls in one piece.
What’s a coped joint and why use it?
A coped inside corner cuts one trim piece to nest against the profile of the other instead of meeting at mitered 45s. It forgives out-of-square corners and stays tight through seasonal wood movement.