Baseboard Length Calculator

Baseboards (also called skirting boards in the UK and Australia) are the trim pieces that run along the bottom of interior walls where they meet the floor. They protect the wall from scuffs and furniture, cover the gap between the wall and floor, and add a finished look to any room.

Calculating baseboard length: The basic formula is the perimeter of the room minus the width of all doorways. But there are several additional factors to account for:

Step 1 — Measure the room perimeter: Measure all four walls and add them together. For non-rectangular rooms, break it into sections and add all wall lengths.

Step 2 — Subtract door openings: For each doorway, subtract the door frame width from the perimeter. Standard interior door openings are about 900mm / 36 inches (frame to frame). You’ll still need baseboard on the sides of the doorway, but not across the opening itself.

Step 3 — Add waste factor: Always order more than your calculated length. Baseboard is mitered at corners (45° cuts), and each miter joint wastes a small amount. Additionally, boards come in fixed lengths (usually 240cm / 8ft, 360cm / 12ft, or 480cm / 16ft in most markets), so you’ll have offcuts.

Standard waste allowance:

• Simple rectangle room: add 10%
• Room with many corners or angles: add 15%

Step 4 — Calculate board count: Divide total length needed by the board length you’re buying.

Metric vs Imperial: This calculator works in both meters/centimeters and feet/inches. All measurements should be in the same unit.

Tips for installation:

• Inside corners: one piece runs to the corner, the second piece is coped (not mitered) for a better fit
• Outside corners: both pieces mitered at 45°
• Seal all gaps with paintable caulk after installation
• Pre-prime and paint baseboard before installing for easier touch-up later