What a trim takeoff actually is
A trim takeoff is a perimeter measurement with three corrections. You measure around the room, take out the length that gets no trim, add the material you will cut off and throw away, and then round up to whole sticks because that is the unit the store sells.
Each correction has a reason. Door and cased openings interrupt the run, and so does anything the base cannot pass in front of — a run of kitchen cabinets, a raised hearth, a full-height bookcase. Waste is not optional: every miter you cut removes material, every stick has a factory end that needs trimming, and every board you cut short becomes an offcut you may or may not use somewhere else. And a store sells 16 ft sticks, not 53.81 linear feet, so the last step is a ceiling function.
The two joint counts on this page matter more than most people expect. The perimeter tells you what to buy; the joint count tells you how long the day will be. Corners take a coped or mitred cut on each side, and long walls take a scarf joint wherever the run exceeds a stick. On a rectangular room with four corners and no scarfs, the base goes on in an afternoon; the same footage broken into a room with ten corners is a different job entirely.
Every term in the deduction, explained
Perimeter is 2(L + W) for a rectangle. For an L-shaped room, split it into two rectangles along the inside corner, run this calculator twice, and add the results — the shared wall lengths cancel because each rectangle contributes the piece of that wall it actually owns. Do not measure at the ceiling; walls are rarely plumb enough for that to be the same number.
Each opening removes its own width plus two casing widths. This is the term takeoffs most often miss. Base does not run behind casing; it dies into the side of it. A 32 in door with 2½ in casings removes 32 + 5 = 37 inches of base, which is 3.08 ft, not 2.67 ft. Over five openings that is a 2 ft difference — not enough to change the stick count, but enough to change it once you also add waste. If the opening is uncased, drop the casing width to zero.
Waste at 10% is the rectangular-room default. Raise it toward 15% when the room has many corners, because every corner consumes a mitre; when you are running a stained hardwood profile and want to reject boards for grain; or when the profile has a repeating pattern that must be aligned across joints. Lower it only if you are working from long clean stock into few long walls.
Scarf joints are counted per wall as ceil(wall ÷ stick) − 1. A 24 ft wall in 16 ft stock needs one; a 34 ft wall needs two. A scarf is cut as a pair of matching 45° bevels landing on a stud, so the overlapping faces stay tight when the wood shrinks in winter — a square butt joint opens into a visible gap.
Material is priced on the ordered footage and labour on the net footage. That is deliberate: you pay the store for the wood you carry out including the waste, and you pay the carpenter for the wall they actually cover.
Worked example: a 12 by 14 bedroom with one door
The room is 14 ft by 12 ft with a single 32 in door cased in 2½ in flat stock. You want painted MDF base at $2.75 a foot, installed by a carpenter at $3.50 a foot, from 16 ft sticks, at a 10% waste allowance.
- Perimeter. 2 × (14 + 12) = 52.00 ft.
- Opening deduction. 32 in ÷ 12 = 2.667 ft for the door, plus 2 × 2.5 in ÷ 12 = 0.417 ft for the two casing legs, giving 3.083 ft.
- Net run. 52.00 − 3.083 = 48.92 ft.
- With waste. 48.92 × 1.10 = 53.81 ft.
- Sticks. 53.81 ÷ 16 = 3.36, rounded up to 4 sticks, which is 64 ft on the truck.
- Material. 53.81 × $2.75 = $147.97.
- Labour. 48.92 × $3.50 = $171.21, so the installed total is $319.18.
Joints: four inside corners and no scarfs, because no wall exceeds 16 ft. Eight coped or mitred ends in total, one per corner per board. Note the gap between the 53.81 ft you pay for and the 64 ft you carry home — four sticks is the smallest whole number that covers the run, and the surplus 10 ft is real material you will have left over, not waste already counted.
How to read the numbers before you buy
Look at the stick count against the ordered footage. If the ceiling function is rounding you up by nearly a whole stick — ordering 49 ft and buying 64 — check whether a shorter stock length wastes less. Four 16 ft sticks is 64 ft; six 10 ft sticks is 60 ft and costs less, but it forces two extra scarf joints on any wall over 10 ft. That trade between money and joints is the real decision, and it is why both numbers are on the page.
Compare the net run against the wall table. If one wall is longer than your stock, the scarf count is non-zero and you should plan which stud the joint lands on before you cut, not after. Scarfs look best when they fall away from the room's main sight line, so put them on the wall behind the door.
The material and labour split is worth reading separately when you are deciding whether to hire out. Trim is one of the few remodelling tasks where labour normally exceeds material on a painted profile, and where the labour buys skill you can see from across the room. On a stained hardwood profile the ratio flips, because the material gets several times more expensive while the labour per foot barely moves.
Finally, treat quarter round or shoe as a second, separate run. It follows the same perimeter but usually skips the same openings, so the net footage is close to identical — run the calculator again with the shoe price and add it.
Baseboard needed for common room sizes
| Room | Perimeter (ft) | Net run (ft) | Order with waste (ft) | 16 ft sticks |
|---|---|---|---|---|
| 8 × 10 | 36 | 32.92 | 36.21 | 3 |
| 10 × 12 | 44 | 40.92 | 45.01 | 3 |
| 12 × 12 | 48 | 44.92 | 49.41 | 4 |
| 12 × 14 | 52 | 48.92 | 53.81 | 4 |
| 12 × 16 | 56 | 52.92 | 58.21 | 4 |
| 14 × 20 | 68 | 64.92 | 71.41 | 5 |
| 16 × 24 | 80 | 76.92 | 84.61 | 6 |
| 20 × 30 | 100 | 96.92 | 106.61 | 7 |
Rows are the formula evaluated at each size, not typed estimates. Add a stick if you are coping rather than mitring inside corners for the first time.
Mistakes that leave you short a stick
- Deducting the door but not the casing. Two casing legs per opening is real footage. Five openings at 2½ in casings is over 4 ft.
- Measuring at the ceiling or over furniture. Base follows the floor line. Measure at the floor, with the tape against the wall, on every wall.
- Forgetting the closet. Closet interiors usually get base, and a reach-in closet adds three short walls with two more inside corners.
- Buying exactly the ordered footage in short sticks. Ordered footage is a length, not a cutting plan. Two 8 ft sticks do not cover a 15 ft wall without a scarf, and a scarf costs material.
- Ignoring the profile change at a stair skirt or a bulkhead. Those transitions need a return or a plinth block, neither of which is in a linear-foot count.
- Assuming shoe molding follows the same deductions. Shoe often continues across a cased opening where base does not, and it stops at any run that meets flooring rather than drywall.
Where this fits in a room finish
Trim is the last linear-foot takeoff in a room and the first one people underestimate, because the perimeter is small compared with the area quantities that come before it. Order flooring and paint by area, base and casing by perimeter, and never derive one from the other.
If you are finishing a whole room, the companion numbers are wall area for paint and wallcovering and floor area for tile or board. The paint coverage calculator handles the wall area including the same door deductions, the wallpaper roll calculator deals with pattern repeat, and the tile quantity calculator covers the floor. If you are milling your own profile from rough lumber, price the stock with the board foot calculator first, since a board foot and a linear foot are different units and the difference is the thickness and width of your profile.
Once the trim is on, the room's remaining decisions are proportional rather than linear: where the pictures hang, how big a rug fits, how far apart the shelves sit. The rug size for room calculator and the shelf spacing calculator pick those up.
Trim terms worth knowing
- Coped joint
- An inside corner where one board is cut square into the corner and the second is back-cut to the exact profile of the first with a coping saw. It stays tight when the corner is not truly 90°, which most corners are not.
- Scarf joint
- A joint in a straight run made from two matching 45° bevels that overlap. Landing it on a stud lets you nail through both faces, and the overlap hides seasonal shrinkage that a butt joint would expose.
- Return
- A short mitred piece that wraps the end of a run back to the wall, so end grain never shows. Common where base dies at a stair skirt or a tiled hearth.
- Shoe molding
- A small quarter-round-like profile nailed to the base, not the floor, to cover the gap at the flooring edge. It is a separate linear-foot run at a separate price.