Baseboard & Trim Calculator
Linear feet, pieces, and cost — doorways subtracted. Free, instant, and private — everything runs on your device.
~3 ft each, no trim across
For miters & mistakes
Your baseboard estimate
- Room perimeter
- 44 ft
- Baseboard needed (less doorways)
- 41 ft
- With waste
- 45.1 ft
- Estimated cost
- $90
Longer stock means fewer joints to splice on long walls, but 16-ft pieces are awkward to transport and cut. Add extra for outside corners, which eat length in miters. The same math works for crown, shoe, and chair-rail trim.
Trim looks like the simplest buy in the store and quietly isn't. Measure a room's perimeter, forget to subtract the doorways, ignore the offcuts every mitered corner wastes, and you'll either overpay or come up a piece short on the last wall — where a splice shows most. This calculator takes your room size, subtracts the doorway openings, adds a waste margin for miters and mistakes, and converts it into the number of pieces to buy at your chosen stock length.
The same math covers baseboard, crown molding, shoe molding, and chair rail — anything sold by the linear foot in fixed lengths. Longer stock means fewer splices on long walls but harder handling; the calculator lets you compare 8-, 12-, and 16-foot pieces.
How it works
No black box — this is the exact math the calculator runs.
- Perimeter = 2 × (length + width), in feet.
- Subtract doorway openings (about 3 ft each — no baseboard runs across a doorway).
- Add a waste percentage (10% default) for miter cuts and mistakes.
- Pieces = trim needed ÷ your stock length, rounded up to whole boards.
- Cost = trim needed (with waste) × your price per foot.
Last reviewed July 24, 2026 · Rooms & Organization
Frequently asked questions
How much baseboard do I need for a 12x10 room?
The perimeter is 44 feet. Subtract one 3-foot doorway and you need 41 feet of baseboard; add 10% for miters and you're buying about 45 feet — six 8-foot pieces. More doorways and closets reduce the run.
How much extra trim should I buy for waste?
10% is a safe default for a straightforward rectangular room. Go to 15% for rooms with many corners, angles, or short walls, where every outside corner burns length in the miter and short walls leave unusable offcuts.
Should I buy longer baseboard pieces?
Longer stock (12 or 16 ft) means fewer scarf joints to splice and hide on long walls, giving a cleaner result. The trade-off is transport and handling — 16-foot trim is unwieldy in a car and awkward to cut accurately alone.
Does this work for crown molding and chair rail?
Yes. Crown, shoe, quarter-round, and chair rail are all sold by the linear foot in stock lengths, so the same perimeter-minus-openings-plus-waste math applies. Crown often warrants a slightly higher waste factor because its compound miters are less forgiving.