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.
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This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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