Baseboard Calculator
Enter your room's perimeter, the total width of any doorway openings, and a waste allowance to calculate exactly how many linear feet of baseboard or trim to buy.
Baseboard needed
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Enter your room details to calculate.
How the Baseboard formula works
Perimeter minus openings, with waste added:
Baseboard needed = (Perimeter − Doorway openings) × (1 + Waste%)
Step-by-step calculation
- Calculate the room's total perimeter (2 × length + 2 × width, for a rectangular room).
- Subtract the combined width of any doorways or large openings, since baseboard isn't needed there.
- Increase the result by your waste percentage to account for cuts and mistakes.
Worked example
A 12 ft × 10 ft room (perimeter 44 ft) with two 3 ft doorway openings, and 10% waste: Needed = (44 − 6) × 1.10 = 38 × 1.10 = 41.8 linear feet.
Frequently asked questions
How much waste allowance should I use for baseboard?
10% is a reasonable general allowance for a simple rectangular room; more complex rooms with many corners or angles may need 15% or more to account for additional cuts and mitered corners.
Does this account for outside corners versus inside corners?
No — this calculates total linear footage needed. Corner type affects how boards are cut and joined (mitered for outside corners, coped for inside corners) but doesn't change the total length of material required.