Baseboard & Trim Calculator
Linear feet of baseboard or trim for a room, with waste.
Input sheet
DIY at your own risk. Calcora's calculators and guides are general estimates and information only — not professional, engineering, legal, or safety advice. Always verify local building codes and permit requirements, and hire a licensed pro for electrical, gas, plumbing, structural, or any work you're not fully comfortable doing yourself.
Baseboard and trim are sold by the linear foot, and the figure that trips people up is subtracting doorways and adding waste for the miter cuts at every corner. This calculator handles both so you buy the right length.
How it works
Room perimeter minus 3 ft per doorway, plus a 10% waste allowance for miter cuts.
Start with the room perimeter, subtract 3 feet for each doorway since trim doesn't cross an opening, then add a 10% waste allowance for the angled miter cuts at inside and outside corners. The result is the linear footage to purchase.
Miter cuts at corners always sacrifice a little material, and a mismeasured corner can ruin a whole stick. The 10% allowance covers those plus the occasional bad cut.
Linear feet = (perimeter − doorways × 3) × 1.1, rounded up.
Worked examples
A 14 ft × 12 ft room with one doorway. → 54 linear feet.
Perimeter = 2 × 26 = 52 ft, minus 3 ft for the doorway = 49 ft × 1.1 = 53.9, rounded up to 54 ft.
A 16 ft × 16 ft room with two doorways. → 64 linear feet.
Perimeter = 64 ft, minus 6 ft for two doorways = 58 ft × 1.1 = 63.8, rounded up to 64 ft.
Tips & gotchas
- Buy a few longer sticks for the longest walls — a single continuous run with no seam looks far cleaner than two pieces scarfed together.
- Cut and dry-fit a couple of corners before committing; inside corners are often coped rather than mitered for a tighter joint.
- Account for closets and alcoves the perimeter formula might miss — walk the room and add any wall the simple length × width didn't capture.
- The same math works for crown molding and chair rail — just measure the relevant perimeter.
FAQ
Should I subtract for windows?
No — baseboard runs under windows along the floor, so only doorways and other floor-level openings reduce the run. The calculator subtracts 3 feet per doorway by default.
Why add 10% waste for trim?
Every corner needs a miter or cope cut that wastes a little material, and a single bad cut can spoil a stick. The 10% allowance keeps you from running short over a roomful of corners.
Does this work for crown molding too?
Yes — the perimeter-minus-openings-plus-waste approach applies to any continuous trim run. Crown often needs a bit more waste because its compound miters are easier to mis-cut.
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