About this tool
The Trim & Molding Linear-Foot Calculator figures out how much baseboard, crown molding, chair rail, or door/window casing to buy for a room. It starts from the room perimeter, calculated as 2 × (length + width) for a rectangular room. Baseboard and chair rail run around the room but stop at door openings, so the tool subtracts the total width of your openings from the perimeter. Crown molding runs continuously across the tops of the walls and ignores doors, so its length equals the full perimeter.
Casing is calculated per opening: a door is trimmed on three sides, so each opening needs 2 × height + width of molding. The tool multiplies that by the number of openings. Whichever trim type you choose, a cut-and-miter waste allowance is added on top — 10 percent is typical for straight profiles, and 15 percent is a safer margin for crown or patterned moldings where every corner is a compound miter.
Results show the net linear feet, the linear feet to purchase once waste is included, and the number of stock lengths to buy — 8, 12, or 16 ft boards — rounded up. The corner count is also reported as a quick guide to how many mitered joints you will cut. All math happens locally in your browser, so nothing you enter is uploaded.