Enter the size of the room and the number of doorways. The calculator works out the length of wall that needs baseboard, adds waste for corner cuts and splices, and tells you how many pieces to buy.
How to use the calculator
- Measure the length and width of the room along the walls.
- Enter the number of doorways and their width; trim does not run across an opening.
- Choose the waste allowance and the length of the pieces sold at your store.
Formula
Wall length = 2 × (length + width) − doorways × doorway width Linear feet to buy = wall length × (1 + waste %) Pieces = linear feet ÷ piece length, rounded up
Worked example: a 14 × 12 ft room with one door
- Perimeter: 2 × (14 + 12) = 52 ft.
- Minus a 3 ft doorway: 49 ft.
- Add 10% waste: 53.9 ft.
- In 12 ft pieces: 5 pieces.
How much extra baseboard to buy
Each inside and outside corner is cut at an angle or coped, and walls longer than your pieces need a splice. A 10% allowance is a common starting point; add more for a room with many short walls, bay windows or closets. Longer pieces mean fewer splices on long walls.
Questions
How much baseboard for a 12 × 12 room?
About 49.5 ft with one 3 ft door and 10% waste, which is 5 pieces of 12 ft.
Do closets count?
Yes. Add the closet walls to the room size, or measure all the walls and enter the total as the length with a width of 0.5.
Should I subtract doorways?
Yes. Baseboard stops at the door casing.
Sources
- NIST Guide to the SI, Appendix B.8: Factors for units listed alphabetically, National Institute of Standards and Technology.
Used for: Exact foot and inch definitions.