Baseboard & trim calculator
Trim is sold by the linear foot in fixed board lengths, and the waste comes from cutting those boards to fit each wall. Enter the room, the openings, and what you are installing, and the calculator returns linear feet and board counts for each kind of trim, plus the nails, caulk, and cost.
How the baseboard and trim calculator works
Baseboard and shoe molding run around the room minus the doorways, so the calculator subtracts the door openings from the perimeter. Crown molding runs the full perimeter. Casing is figured per opening: two legs of about 7 ft plus the head piece and a little for reveals, times one or both sides of each door, and about 14 ft per window.
Each total is turned into boards by dividing by your board length with 10 percent waste for baseboard and 15 percent for crown and casing, which have more angled cuts. Buying 16 ft boards gives the fewest joints; 8 ft boards fit in a car.
Formula
baseboard ft = perimeter − doors × opening width
casing ft = doors × sides × (14 + opening width + 0.5) + windows × 14
boards = ceil(linear feet × 1.1 ÷ board length)
Example: a 14 × 12 ft room has 52 ft of wall. With two 3 ft doors it takes 46 ft of baseboard and 46 ft of shoe, which is 4 boards of 16 ft for each. Casing both sides of the doors and two windows adds 98 ft, or 8 more boards.
Choosing and installing trim
| Material | Cost per ft | Notes |
|---|---|---|
| Primed MDF | $1 to $2 | Cheapest, smooth, paints well. Swells if wet; not for baths. |
| Primed finger-joint pine | $1.50 to $3 | Holds nails better than MDF, paint grade only. |
| Solid pine or poplar | $2 to $4 | Can be stained; poplar paints best. |
| Oak and hardwoods | $4 to $8 | Stain grade, matches hardwood floors. |
| PVC | $2 to $4 | Waterproof for bathrooms, laundry, basements. |
- Baseboard height scales with ceiling height: 3 1/4 in for 8 ft ceilings, 5 1/4 in for 9 ft, 7 in or more for 10 ft.
- Install baseboard after flooring for hard floors, before carpet (leave a 3/8 in gap for the carpet to tuck under).
- Shoe molding hides the gap between baseboard and floor; use it with hard floors and skip it with carpet.
Painting the trim? The paint calculator figures a quart per 100 to 150 linear feet of baseboard. Laying the floor first? See the flooring calculator.
Common sizes, already worked out
Common questions
How much baseboard do I need for a 12x12 room?
48 ft of perimeter minus about 3 ft per door. With one door that is 45 ft, or 50 ft with 10 percent waste. That is five 12 ft boards or four 16 ft boards.
How do I calculate linear feet for trim?
Add up the length of every wall the trim runs along. For baseboard, subtract the width of each doorway. For a whole house, measure each room separately and add 10 percent for cuts and mistakes.
How much casing do I need per door?
About 17 ft per side for a standard 3 ft door: two 7 ft legs plus a 3 ft head and a bit for the reveals. Casing both sides is 34 ft, so one 16 ft board per side with a short piece to spare.
Should baseboards be installed before or after flooring?
After hard flooring (tile, hardwood, laminate, vinyl plank), so the baseboard covers the expansion gap. Before carpet, held 3/8 in off the subfloor so the installer can tuck the carpet edge underneath.