Baseboard and Trim Calculator
Linear feet and stock lengths of baseboard or crown moulding, after deducting doorways.
Trim is bought in fixed lengths and installed in runs, which makes the arithmetic different from flooring or paint. You are not ordering an area, you are ordering the least number of eight or sixteen foot sticks that will cover the walls with as few joints as possible.
Two numbers decide the outcome: the net run after doorways, and the stock length you choose. Longer stock means fewer joints and a cleaner wall, but more waste on short runs. On a room with four doorways and a chimney breast, sixteen foot lengths can waste more than they save.
How this calculator works
Every field is editable and the result updates as you type — nothing is submitted anywhere, all the maths runs in your browser. That matters for a number you are about to spend money on: you can see exactly which input moved the answer, and by how much.
What this calculation assumes
Assumes a rectangular room, standard 3 ft doorways and trim installed with butt joints on long runs. Outside corners, angled walls, full-height cabinetry and any run longer than the stock length will use more material than this allows.
Treat the result as an order-of-magnitude check rather than a final quantity. Product packaging changes, regional labour rates vary by a factor of two, and no calculator has seen your actual site.
Frequently asked questions
Should I deduct doorways?
Yes for baseboard — nothing runs across an open doorway, so deduct roughly three feet per opening. Do not deduct windows at baseboard height, since the baseboard continues under them. For crown moulding the opposite is true: deduct both, plus the width of any full-height cabinet run.
8 ft or 16 ft lengths?
Sixteen foot lengths give fewer joints and a noticeably better wall, but they are awkward to carry and need more waste allowance on short runs. Eight foot is easier to transport and handle alone. If you are working solo in a small room, eight foot is usually the better trade.
How much waste should I allow?
Ten percent for a simple rectangular room cut square. Go to 15% for rooms with many corners, outside corners that need mitres, or any wall longer than your stock length where you must splice. Outside corners always waste a few inches per cut.
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