Baseboard Calculator
This baseboard calculator gives the linear feet a room needs, how many sticks of trim that is at your stock length, and the cost, with doorways deducted and corners counted.
One Room
Several Rooms
Trimming a whole floor. Leave a room blank if you are not using it.
Baseboard Cost
How to use the Baseboard Calculator
Enter the room dimensions and the tool works the perimeter for you, then takes the doorways off. If the room is not a plain rectangle, use Several Rooms and treat each leg as its own rectangle, or measure the walls and add them up yourself.
Set the stock length you actually buy. That matters more than it looks: trim is cut with mitres and scarfs, and you cannot join two sticks mid-wall without the joint showing, so the piece count is driven by the longest walls rather than by the total footage.
Baseboard Cost runs the same measurement and prices it either by the linear foot or by the piece. It is worth checking both ways, a longer stock length wastes more offcut but needs fewer joints.
Baseboard formula
perimeter = 2 × (length + width)net linear feet = perimeter − (doorways × door width)with waste = net × (1 + waste%)sticks = ceiling(with waste ÷ stock length)
Corners are counted separately because they drive the waste: every inside corner is a coped or mitred cut and every outside corner is two mitres, and a botched mitre costs a foot of trim.
| Stock | Suits | Note |
|---|---|---|
| 8 ft | Small rooms, closets | Cheapest per foot, most joints |
| 12 ft | Most rooms | The usual compromise |
| 16 ft | Long walls, open plan | Fewest joints, awkward to carry and to cut |
Worked example
A 16 × 12 ft room with two 3 ft doorways, 12 ft stock, 10% waste:
- Perimeter: 2 × (16 + 12) = 56 ft
- Doorways: 2 × 3 = 6 ft deducted
- Net: 50 ft
- Plus 10%: 55 ft
- Sticks: 55 ÷ 12 = 4.58 → 5 sticks of 12 ft
- Corners: 4 inside
Five sticks is 60 ft for 50 ft of wall. That looks wasteful until you notice the 16 ft walls: each needs a full 12 ft stick plus a 4 ft piece, and the offcuts are what the 10% is really covering.
What the result means
Linear feet tell you the quantity; stock length tells you the order. Fifty linear feet is not four and a bit sticks, it is five, because trim is cut to walls and the leftovers rarely line up with the next wall.
Buy the long walls first. If a wall is longer than your stock, it needs a scarf joint, which should fall on a stud and be glued. Choosing 16 ft stock for a 14 ft wall avoids the joint entirely and is usually worth the extra cost per foot.
Doorways come off, cased openings usually do not. Baseboard dies into the casing on both sides of a door, so the door width comes out. An arch or cased opening with no casing may still need trim across it.
Common mistakes
- Buying by the linear foot and ignoring stock length. The most common cause of a second trip.
- Forgetting that the room is not the wall. Closets, alcoves, chimney breasts and bay windows all add perimeter that a length-times-width figure misses.
- Deducting the door slab instead of the opening. Take off the full cased opening width, not the door leaf.
- Skimping the waste on a room with many corners. Ten percent suits a plain rectangle. A room with six corners and a bay wants fifteen.
- Ordering exactly. Trim gets damaged, mitres get cut backwards, and dye or grain matching matters on stained work. Buy the spare stick.
Frequently asked questions
How do I calculate how much baseboard I need?
Add up the perimeter of the room, subtract the width of every doorway, then add ten percent for waste. Divide that by the stock length you are buying to get the number of sticks, and round up. A 16 by 12 foot room with two 3 foot doors needs 50 linear feet, or five 12 foot sticks.
How many linear feet of baseboard for a 12×12 room?
Forty-eight linear feet of perimeter, less the doorways. With one 3 foot door that is 45 feet, and with ten percent waste about 50 feet, which is five 12 foot sticks or four 16 foot sticks.
Should I subtract doorways from baseboard?
Yes. Baseboard stops at the door casing on each side, so the full width of the cased opening comes off. Deduct the opening, not the door leaf, and leave closet openings in if they are trimmed inside.
How much waste should I add for baseboard?
Ten percent for a plain rectangular room, fifteen for anything with lots of corners, a bay window or a stained finish where you are matching grain. Mitres are unforgiving and a wrong cut costs the better part of a foot.
What length baseboard should I buy?
Long enough to run your longest wall in one piece if you can. A joint in the middle of a wall always shows eventually, whereas an extra dollar per foot does not. Sixteen foot stock for walls over twelve feet, twelve foot stock otherwise.
Do I cope or mitre inside corners?
Cope them. Inside corners in a house are rarely exactly ninety degrees and they move with the seasons, so a coped joint stays tight where a mitre opens up. Outside corners have to be mitred.
Sources and assumptions
Perimeter is computed from the room dimensions entered as a rectangle. Alcoves, closets, bays and chimney breasts add wall length that a rectangle does not capture, measure those separately.
Stock lengths of 8, 12 and 16 ft reflect common US trim packaging; other lengths exist and vary by profile and supplier.
Corner counts assume a rectangular room: four inside corners, no outside corners. Rooms with more complex plans will differ.