Calculator

Room Length (ft)

Room Width (ft)

Doorways

Windows

Door Width (ft)

Door Casing per Door (ft)

Window Casing per Window (ft)

Waste Percentage (%)

Total Trim Needed

Baseboard

Crown

Door Casing

Window Casing

Baseboard runs the full room perimeter minus each doorway's width; crown molding runs the full perimeter uninterrupted, since it sits above door height. Casing footage per opening is an average — measure yours for anything non-standard.

Enter a room's dimensions and its doors and windows to find the total linear footage of baseboard, crown, and casing needed.

How to Use the Trim and Molding Calculator

Room length and width set the perimeter. Doorways and windows each subtract or add their own footage, and both come with an editable per-opening casing default you should swap out for anything non-standard.

Baseboard runs the perimeter but stops at every doorway, since a doorway is a gap in the wall at floor level; crown molding runs the full, uninterrupted perimeter, since it sits above door height where the wall is continuous:

perimeter = 2 × (room length + room width)
baseboard = perimeter − (doorways × door width)
crown = perimeter

Door casing and window casing are added separately on top of those two totals, each using a footage-per-opening default (17 ft for a standard door, 14 ft for a mid-size window) that approximates the legs-plus-head measurement around a typical opening. Real doors and windows aren't all typical, so measure anything oversized, arched, or otherwise unusual and overwrite the default for that room. Waste percentage at the end covers miter cuts and the odd mismeasure — 10% is a reasonable floor for a room without much unusual trim.