Trim Molding Calculator

Calculate baseboard, casing, or crown molding linear feet for a room.

Molding Needed
— linear feet
Includes waste.

Usage Tip

Buy molding in the longest lengths that fit your walls to minimize seams, and cut scarf joints where you must join pieces.

THE MATH
linear feet = (perimeter − doors × door width) × (1 + waste ÷ 100)
Trim runs around the room perimeter, skipping door openings. The linear feet needed is the perimeter minus the door widths, plus a waste allowance for miter cuts.
Enter the room perimeter, the number of doorways and their width, and a waste percentage (15 percent suits mitered trim).
The result is total linear feet to buy.
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The calculators and tools on Formula Factory are provided for general guidance and informational purposes only. Results are estimates based on standard formulas and the values you enter — they do not constitute professional engineering, electrical, or architectural advice. Always verify calculations with a qualified professional before making decisions for any safety-critical, code-compliance, or commercial application. Formula Factory makes no representations or warranties as to the accuracy or completeness of any result, and accepts no liability for errors, omissions, or any outcomes arising from reliance on this information.