Baseboard & Trim Calculator
Find the linear footage of baseboard or crown molding and how many stock lengths to buy.
How to use the Baseboard & Trim Calculator
- Enter the room length and pick its unit.
- Enter the room width and pick its unit.
- Enter the number of doorways – Use 0 for crown molding, which runs over doorways.
- Enter the doorway width (incl. casing) and pick its unit.
- Choose the stock length.
- Enter the waste allowance – Covers miter and coped corner cuts.
- Enter the price per linear foot.
- Press Calculate. The result updates automatically as you type, and you can switch the result unit at any time.
About the Baseboard & Trim Calculator
Baseboard is interrupted at every doorway, while crown molding continues around the whole room, so set doorways to zero for crown. Closets, bump-outs and stair skirts add footage; measure each wall segment and total them if the room is not a simple rectangle.
Buy the longest lengths you can handle so most walls are a single piece without visible scarf joints. Ten percent extra covers miters and coped inside corners in a typical room; add 15% for rooms with many short wall segments or if you're new to cutting crown.
Formula
Net perimeter = 2 × (Length + Width) − Doorways × Doorway width
Linear feet = Net perimeter × (1 + waste %)
Pieces = ⌈Linear feet ÷ Stock length⌉
Cost is based on the full stock lengths you buy, because trim is sold by the piece.
Example calculation
Using the default values:
- Room length = 14 ft
- Room width = 12 ft
- Number of doorways = 1
- Doorway width (incl. casing) = 36 in
- Stock length = 12 ft
- Waste allowance = 10%
the calculator returns:
- Trim needed (incl. waste): 53.9 ft
- Pieces to buy: 5 pieces
- Net perimeter: 49 ft
Frequently asked questions
How do I calculate baseboard for a room?
Add up the length of all walls (2 × length + 2 × width for a rectangle), subtract the width of each doorway, and add about 10% for cuts.
How much baseboard for a 12 × 12 room?
The perimeter is 48 ft. Minus one 3 ft door that is 45 ft, or about 50 ft with 10% waste: five 12 ft pieces or four 14 ft pieces.
Should I buy 8 ft or 16 ft trim?
Longer pieces mean fewer joints and less waste on long walls, but 8 ft lengths are easier to transport and fine for small rooms.
Last updated: · Category: Construction calculators