Baseboard Length Calculator

Room size
For rectangular rooms, enter length and width. For L-shaped or complex rooms, measure the entire wall length around the room and enter that as perimeter.

Openings to subtract
Doorways are typically 32 inches. Wide openings include cased openings, archways, fireplaces – enter their total width in feet (not inches).

Baseboard stock
Big-box stores carry 8 ft and 12 ft. Lumber yards stock 16 ft, which means fewer seams in long walls. Choose the longest length you can transport.

Baseboard needed
Net perimeter
0 ft
after openings
Total to buy
0 ft
with waste
Pieces to buy
0
of selected stock
Caulk needed
0
tubes paintable
Buy 10-15% extra to account for miter cuts, coped joints, and mistakes. Each outside corner needs about 4 inches of extra length. Caulk both the top edge (where it meets the wall) and the joints between pieces. Painted baseboard looks best with caulk – stain-grade trim should be coped instead.

Frequently Asked Questions

How do I calculate how much baseboard I need for a room?

Measure the perimeter of the room (add up the length of all four walls), then subtract the width of any doorways or openings. Add 10% extra to account for cuts, waste, and mistakes.

Should I subtract door and window openings from my baseboard measurement?

Subtract doorway widths since baseboard doesn't run through them. Windows don't need to be subtracted since baseboard runs along the floor, not the wall height where windows sit.

How much extra baseboard should I buy for waste?

Add 10-15% to your total footage to cover angled cuts at corners, mistakes, and mismatched pieces, especially in rooms with lots of corners or angles.

What length do baseboards come in?

Baseboard typically comes in 8, 12, 16, and sometimes 20-foot lengths. Buying longer pieces reduces the number of seams you'll need on long walls.

Do inside and outside corners use baseboard differently?

Inside corners use a coped or mitered joint where two pieces meet at an angle, while outside corners typically need a mitered 45-degree cut on both pieces. Both use the same material, just different cuts.