Baseboard is sold by the piece, in lengths from 8 to 16 feet, so "linear feet plus 10%" is only half an estimate. What matters is whether each wall can be covered by one board, how long the leftovers are, and whether those offcuts fit the short runs beside doors and closets. This baseboard calculator takes your wall runs one at a time. It cuts any run longer than a board into full boards plus a remainder, adds a cutting allowance for copes and miters, and packs the pieces onto boards (longest first) to show how many you need. It also reports a plain linear-feet estimate with your waste percentage, so you can buy the larger of the two. The same method works for shoe molding, quarter round, chair rail and crown.
Replacing flooring at the same time? Use the flooring calculator. The paint calculator covers the walls.
How to use the baseboard & trim calculator
- Measure each wall along the floor. Where a door interrupts a wall, enter the pieces on each side as separate runs, stopping at the door casing.
- Include closets and short returns. Every run will be a separate piece.
- Choose the board length you’ll buy. Longer boards mean fewer joints but are harder to transport.
- Keep a cutting allowance of 2–3 in per piece for squaring factory ends and fitting copes and miters.
- Buy the larger of the cut-list count and the linear-feet count, plus a spare board if the profile may be hard to match later.
Formula
The packing step is the "first-fit decreasing" method: take the longest piece, put it on the first board with room for it, and open a new board only when none has room. It is a simple, reliable way to plan cuts and is usually close to the best possible layout for small jobs like a room of trim.
Worked example
A 16 × 14 ft room with one door on the east wall (runs of 14, 4.5, 8.5, 14 and 16 ft), 12 ft boards, 3 in allowance.
- Total: 57 linear ft.
- Pieces: 14 ft → 12 + 2.25; 4.5 → 4.75; 8.5 → 8.75; 14 → 12 + 2.25; 16 → 12 + 4.25.
- Packing onto 12 ft boards: three full 12s, then 8.75 + 2.25 = 11, 4.75 + 4.25 + 2.25 = 11.25, so 5 boards of 12 ft (60 ft).
- The linear-feet check gives 57 × 1.10 ÷ 12 = 5.2, so 6 boards. Buy 6, which leaves a spare for a mistake.
- Joints: the three walls over 12 ft each need one scarf joint.
Joints and corners
Inside corners are usually coped: one board runs square into the corner and the next is cut to the profile of the first. Bob Vila's installation guide notes that a coped inside corner gives a tighter fit than a miter, while outside corners are mitered. Where a wall is longer than your boards, join two pieces with a scarf joint (overlapping 45° cuts) over a stud rather than a square butt joint, which opens as wood moves. Nail at stud locations, roughly every 16 inches, and into the bottom plate.
Boards, profiles and finishing
Primed MDF, finger-jointed pine and solid hardwood all come in 8 to 16 ft lengths, though not every profile is stocked in every length. Check before planning around 16-footers. Profiles can vary between batches and brands, so buy the whole job at once. If you're adding shoe molding or quarter round to cover a flooring gap, it runs the same lengths, minus any runs where cabinets sit. Caulk the top edge and fill nail holes before the final coat of paint.
Caveats and assumptions
- Runs are treated as straight; bay windows and angled walls need a piece per face.
- The cut list does not reuse offcuts shorter than any remaining piece; real installers may use short scraps for returns.
- Board lengths are nominal; some stock is a little longer or shorter, so measure it.
- For stained hardwood, buy extra so you can match grain and color.
Frequently asked questions
How do I calculate how much baseboard I need?
Add the lengths of every wall run, leaving out doors and built-in cabinets, then add about 10% for cuts. Or list the runs here to pack them onto real board lengths.
How many feet of baseboard for a 12 × 12 room?
The perimeter is 48 ft. Less a 3 ft door opening, about 45 linear ft, or four 12 ft boards with a little to spare.
Should I buy 8, 12 or 16 ft baseboard?
Use boards long enough to cover most walls in one piece to avoid joints, provided you can transport and handle them.
How do I join baseboard on a long wall?
Use a scarf joint (two overlapping 45° cuts) over a stud, glued and nailed, rather than a butt joint.
Do I subtract doors from baseboard length?
Yes. Baseboard stops at the door casing, so measure each wall section between casings separately.
Sources
- Bob Vila — How to Install Baseboard and Cut Baseboard Corners — coped inside corners, mitered outside corners, nailing at studs
- NIST SP 811, Appendix B — conversion factors — feet to meters
- Johnson, Demers, Ullman, Garey & Graham — Worst-case performance bounds for simple one-dimensional packing algorithms (SIAM J. Computing, 1974) — first-fit decreasing packing
This calculator gives estimates for planning and education. Check measurements, local codes, supplier specs and your school's official policy before relying on a result. See our disclaimer and how we build and check calculators.