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This baseboard calculator works out how much baseboard trim you need for one or more rooms. It measures the room perimeter, subtracts doorways, adds an allowance for miters and cuts, and tells you how many pieces to buy in the lengths sold at the store.
How to Use the Baseboard Calculator
- Enter the room length and width.
- Enter the number of similar rooms.
- Enter the number and width of doorways in each room.
- Choose the length of trim pieces and a waste allowance.
Baseboard Formula
Linear feet = 2 × (Length + Width) − Doorway widths
Pieces = Linear feet × (1 + waste %) ÷ Piece length
For L-shaped rooms, closets and alcoves, measure each wall and add them up instead of using length and width.
Example
A 14 × 12 ft room has a perimeter of 52 ft. Subtracting one 3 ft doorway leaves 49 ft. With 10% extra you need 54 linear feet, or 4 pieces of 16 ft baseboard.
Choosing Piece Lengths
- Longer pieces (12–16 ft) mean fewer joints on long walls.
- Shorter pieces (8 ft) are easier to transport but need more scarf joints.
- Buy enough so each wall can be covered in one piece where possible.
Other Trim You Can Calculate
- Shoe molding and quarter round: same length as the baseboard.
- Crown molding: use the full ceiling perimeter without subtracting doorways.
- Chair rail: the perimeter minus doorways and any windows that interrupt it.
Painting the room as well? Try the paint calculator.
Frequently Asked Questions
How much baseboard do I need for a 12×12 room?
The perimeter is 48 ft. Subtract about 3 ft per doorway and add 10% for cuts: roughly 50 linear feet.
How do you measure for baseboard?
Measure the length of every wall at floor level, add them together and subtract the width of door openings.
How much extra baseboard should I buy?
Add about 10% for miter cuts and mistakes, or 15% for rooms with many corners.
What lengths does baseboard come in?
In the US baseboard is commonly sold in 8, 12 and 16 ft lengths; in the UK and Europe, 2.4–4.2 m.
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