How to measure baseboard
Baseboard is bought by the piece and measured in linear feet. Add up the length of every wall that gets trim (for a rectangle, 2 × (length + width)), subtract door openings measured casing to casing, subtract cabinets, tubs and built-ins, and add about 10% for copes, miters and cut-offs. Closets count: add each closet as its own room.
Worked example — a 12 × 14 ft bedroom with one door: 2 × (12 + 14) = 52 ft. Minus a 3 ft door opening = 49 ft. With 10%, 53.9 ft. In 12 ft pieces that is 5 pieces, and the full 14 ft wall is longer than a stick, so it needs 1 scarf joint. In 16 ft pieces you need 4, with no splices at all.
Pick the piece length before you buy
The calculator plans every wall onto sticks of 8, 12 or 16 ft and shows the cut list. It takes the larger of two counts: total length plus your waste allowance, and the number of sticks needed so that no wall shorter than a stick has a joint in it. Longer pieces mean fewer joints but are harder to haul; 8 ft fits in most cars.
| Room (1 door) | Linear ft | 8 ft pieces | 12 ft pieces | 16 ft pieces |
|---|---|---|---|---|
| 10×10 ft | 37 | 6 (3 splices) | 4 | 4 |
| 10×12 ft | 41 | 6 (4 splices) | 4 | 4 |
| 12×12 ft | 45 | 7 (4 splices) | 5 | 4 |
| 12×14 ft | 49 | 7 (4 splices) | 5 (1 splice) | 4 |
| 12×16 ft | 53 | 8 (4 splices) | 5 (2 splices) | 4 |
| 15×20 ft | 67 | 10 (6 splices) | 7 (4 splices) | 5 (2 splices) |
Corners and joints
- Inside corners: butt one piece square into the corner and cope the other to its profile, or miter both at 45°. Lowe's install guide shows both; coping hides small gaps better when corners aren't square.
- Outside corners: miter both pieces at 45°.
- Long walls: join two pieces with a scarf joint — opposing 45° cuts that overlap — over a stud.
- Door casings: square cuts where the base meets the casing.
Nails, caulk and paint
Lowe's guide calls for finishing nails into the studs every 16–18 in; carpenters typically drive two per stud, one high and one low, which works out to about 1.5 nails per linear foot. For the top edge, DAP rates a 10.1 oz tube of Alex Plus at 55 linear ft with a 3/16 in bead. Paint area is linear feet × height ÷ 12 (the Sherwin-Williams calculator method): 45 ft of 5¼ in base is about 20 sq ft, and at 350–400 sq ft per gallon per coat, two coats fit in a single quart.
Quarter round with new floors
If the baseboards stay in place over a new floating floor, quarter round or shoe molding covers the expansion gap — 1/4 in for vinyl plank, 3/8 in for laminate. Nail it to the baseboard, not into the floor. A 3/4 in solid-hardwood gap is wider than standard quarter round covers, so pull and reset the baseboards instead. The flooring calculator adds quarter round to the flooring list automatically.
What it costs
Angi's 2026 figures put MDF baseboard at $1.00–$1.40 per linear foot and professional installation at $5–$7.75 per linear foot, so labor is most of the bill. Painting and removing old trim are usually quoted separately.
Common mistakes
- Buying exactly the perimeter with no allowance for copes and bad cuts.
- Splicing short walls with leftover pieces — buy enough length that every wall under one stick is a single piece.
- Forgetting closets, or counting a door between two trimmed rooms only once.
- Nailing into drywall between studs, where nails don't hold.
Planning a room refresh? Pair this with the paint calculator for the walls and the carpet calculator or tile calculator for the floor.