How this calculator works. Perimeter = 2 × (length + width), minus doorway widths (3 ft standard). We add your waste factor — 10% default, covering miters that get re-cut and the rule that outside corners and long walls prefer single uncut pieces — and divide by stick length, rounding up.
Baseboard math and the miter tax
Trim waste isn't like flooring waste — it comes from corners. Every inside corner is a coped or mitered joint, every outside corner a precise 45° pair, and a miter cut a degree off (walls are never square) means recutting an inch shorter each attempt. Beginners should take the 10%; on a first trim job, 15% isn't shameful.
Stick length is a strategy choice: longer sticks mean fewer mid-wall splices (which open into visible gaps as wood moves seasonally), so buy sticks longer than your longest wall where possible. A 16-ft stick is awkward in a hatchback but makes a 15-ft wall seamless.
Per-room extras
| Item | Rule of thumb |
|---|---|
| Finish nails (2" / 18-ga brads) | One small box does several rooms |
| Paintable caulk | 1 tube per ~40 linear ft (top edge + corners) |
| Wood filler | One tub — nail holes + miter gaps |
| Construction adhesive | For metal studs or bowed walls only |
Buying tips
MDF trim is straight, cheap, and paints beautifully — the right call for painted baseboard in dry rooms. Use real wood (or PVC) in bathrooms and anywhere moisture lives; MDF swells like a sponge at the first mop-water contact. Prime the back and cut ends of MDF if the floor gets wet-mopped.
Common questions
Do I really subtract doorways?
Yes for baseboard — it stops at casings. But if you're also replacing door casing, that's a separate count: about 17 linear ft per door (both sides + head, one side of wall) — our calculator's "also grab" line reminds you.
Cope or miter inside corners?
Coping (back-cutting one piece to the profile of the other) survives seasonal movement; miters open into gaps. Cope inside corners, miter outside ones — the pro standard for a reason.
Nail into studs or just the wall?
Into studs (top of the baseboard) and the bottom plate (bottom edge, always solid wood behind). Adhesive-only jobs telegraph every wall wave and pop off with the first vacuum hit.
Quarter-round: needed or not?
It covers the gap where flooring meets baseboard. New floor under existing baseboard: yes. New baseboard installed after flooring, tight to the floor: optional — style call.