Baseboard Calculator
Work out the linear feet of baseboard trim a room needs from its size and door openings, plus how many 8-ft or 16-ft pieces to buy.
How it works
perimeter = 2 × (length + width) · net = perimeter − doors × door width · buy = net × 1.10
Baseboard runs around the base of every wall, so the starting figure is the room perimeter — twice the length plus width. Door openings get no baseboard, so subtract each door’s width. Adding about 10% covers the offcuts from mitred inside and outside corners and scarf joints on long walls, plus the odd miscut. Rounding the total up to whole 8-ft or 16-ft stock lengths tells you how many pieces to carry home.
Worked example
A 15 × 12 ft room has a perimeter of 2 × (15 + 12) = 54 ft. Two 3 ft doors remove 6 ft, leaving 48 ft; with 10% waste that is 52.8 ft — seven 8-ft pieces or four 16-ft pieces.
Frequently asked questions
How much waste should I add for baseboard?
About 10% for a normal room. Every inside and outside corner is a mitred cut that leaves an offcut, and long walls need scarf joints. Rooms with lots of corners, closets or angles run higher, so bump it to 15% if the layout is busy.
Do I subtract for doors and not windows?
Subtract door openings, since baseboard stops at the casing and does not cross a doorway. Windows sit above the baseboard, so they do not interrupt the run — leave the full wall length under a window in the count.
Should I buy longer pieces?
Longer stock (16 ft) means fewer scarf joints on long walls, which looks cleaner and is easier to finish, but it is harder to transport and handle. Match the piece length to your longest walls and what your vehicle and doorways can accommodate.
Related calculators
Estimate for planning. Add a waste margin and confirm against your supplier specs and local building codes.