Baseboard Trim Length Calculator
Calculate linear feet of baseboard trim for any room.
Enter dimensions and door count to get total length plus board quantity at 8 and 12 ft.
Baseboard runs along every wall, so you start with room perimeter: 2 × (length + width). Then subtract doorway openings — baseboard stops at the door casing on each side. Add a waste factor for miter cuts and any boards you nick on a bad cut.
Net perimeter = 2 × (L + W) − (doors × door width) Total needed = net perimeter × (1 + waste%)
For a 12 × 10 room with one 3-ft doorway and 15% waste: Net = 44 − 3 = 41 ft Total = 41 × 1.15 = 47.2 linear feet
The result also shows how many boards you need at 8 ft and 12 ft. Long boards mean fewer seams. On an unbroken wall, a single 12-ft piece looks cleaner than two 8-footers spliced together, especially with a painted profile that shows the joint.
Outside corners need 45-degree miters on both boards; inside corners get a coped joint (one board butts square, the other is cut to match the profile). Either way you lose 2–3 inches per cut. The 15% default handles a normal room. If you have more than four outside corners, bay windows, or angled walls, bump it to 20%.
Buy a little extra if the profile is unusual. An exact match can be impossible to find six months later when you need to patch a scuffed section. Paint-grade MDF baseboard is easier to match than stain-grade solid wood; for stain-grade, always overbuy on the first purchase.
Baseboard height affects the order too. 3-inch base is standard; 5 or 7-inch colonial profiles cost significantly more per linear foot. If you are mixing height, calculate each section separately.