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Baseboard Calculator
Use this free baseboard calculator to find out how many baseboards you need for a room or a whole project. Enter the room length and width — or the total linear feet if you have already measured the walls — pick your board length, add a waste allowance, and the calculator gives the total linear feet, the number of boards to buy, and the cost if you enter a price per board. Buying the right count the first time saves a second trip to the store and keeps offcuts to a minimum.
How it works
Baseboard is sold by the linear foot, but it comes in fixed-length boards, so the job is really two steps: find the total length of wall to cover, then divide that length into boards. For a plain rectangular room, the wall length is the perimeter — two times the length plus two times the width. A 12-by-10-foot room has a perimeter of 44 feet. If you have already measured every wall, skip the room size and enter the total linear feet directly; that mode also covers L-shaped rooms, hallways, and whole-house jobs where a single rectangle does not describe the space.
Doorways need no baseboard. The board stops at the door casing on each side, so the opening itself is empty. This calculator subtracts about 3 feet for each standard doorway you enter — the width of a typical interior door plus its casing. If a doorway is wider, such as a double door or a wide cased opening without a door, count it as two doorways or measure the opening and use the linear-feet mode with the opening already subtracted. Closet openings and wide archways count the same way: anywhere the wall is open, no board runs across it.
Waste is the part most people forget, and it is why a job measured at exactly 44 feet needs more than 44 feet of board. Boards are cut to fit each wall, and the offcut from one wall rarely fits the next one exactly. Corners need angled cuts, ends get trimmed square, and one bad cut or a damaged end eats a whole board length. Ten percent is the standard allowance for a room with mostly straight runs; fifteen percent suits rooms with many corners, bay windows, or short wall pieces between doors; twenty percent is for complex rooms with angled walls. The calculator multiplies the net wall length by one plus the waste rate — 44 feet at 10 percent becomes 48.4 feet.
The board count is the total feet with waste divided by the board length, rounded up. You cannot buy part of a board, so 48.4 feet divided by 8-foot boards is 6.05, which rounds up to 7 boards. Longer boards reduce the count and the number of joints: the same 48.4 feet needs only 5 boards at 10 feet (4.84 rounded up) and 4 boards at 12 feet (4.03 rounded up). Fewer joints look better along a long wall, but long boards are harder to carry upstairs and around corners, so 8-foot boards are the practical choice for small rooms and tight stairways, while 12- and 16-foot boards suit open rooms and whole-house runs.
If you enter a price per board, the calculator multiplies the board count by that price for the material cost. Remember that the total job usually costs more than the boards alone: finishing nails or adhesive, caulk for the top edge, wood filler for nail holes, primer, and paint or stain all add up, and a painted finish needs a second trip over the boards after installation. Buying one spare board beyond the calculated count is cheap insurance — it covers a miscut without a return trip, and leftover baseboard in the same profile is useful for future repairs.
Measure twice before you order. Run a tape along the base of each wall, wall by wall, and write each length down; do not measure the floor area and guess. Walls are rarely exactly the size on a plan — framing, drywall, and plaster shift dimensions by an inch or two — and a tape measure at the wall is the only number that counts. Check the board profile and height while you are at it: 3-1/4-inch and 5-1/4-inch are the common heights, and matching the existing profile in the rest of the house matters more than the exact height.
Worked example
A bedroom measures 12 feet long and 10 feet wide, with no doorways to subtract, using 8-foot boards and a 10 percent waste allowance.
Step 1: Perimeter — 2 × (12 + 10) = 44 linear feet.
Step 2: Doorways — none, so the net length stays 44 feet.
Step 3: Add waste — 44 × 1.10 = 48.4 feet.
Step 4: Board count — 48.4 ÷ 8 = 6.05, rounded up to 7 boards.
Step 5: Cost — at $12.50 per board, 7 × $12.50 = $87.50.
You need 7 boards of 8-foot baseboard, costing $87.50 at $12.50 per board. With 12-foot boards instead, the same job needs 5 boards (48.4 ÷ 12 = 4.03, rounded up), which would cost $62.50 at the same per-board price — but only if the longer boards fit in your vehicle and around the corners.
FAQ
How do I measure a room for baseboards?
Measure the length of every wall that will get baseboard and add the lengths together. For a plain rectangular room, that is the perimeter: two times the length plus two times the width. Subtract about 3 feet for each doorway with no door, since no baseboard runs across a doorway opening.
How much waste should I add for baseboards?
Add 10 percent for a room with mostly straight runs and few corners, and 15 percent for a room with many corners, angles, or short wall pieces. Waste comes from cutting boards to length, trimming damaged ends, and matching joints at corners. This calculator defaults to 10 percent.
What length do baseboards come in?
Common stock lengths are 8, 10, 12, and 16 feet. Longer boards mean fewer joints along a wall, which looks better, but they are harder to carry and cut. An 8-foot board suits small rooms and cars, while 12- and 16-foot boards suit long walls and whole-house jobs.
Do I count doorways when measuring baseboard?
No. Baseboard stops at the door casing on each side of a doorway, so the opening itself needs no baseboard. Subtract about 3 feet per standard doorway, or measure the actual opening width if the doorway is wider than standard, such as a double door or a wide cased opening.
How many baseboards do I need for a 12 by 10 foot room?
The perimeter is 2 times 12 plus 2 times 10, which is 44 linear feet. Adding 10 percent waste gives 48.4 linear feet. With 8-foot boards, that is 48.4 divided by 8, which is 6.05, rounded up to 7 boards.