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Crown Molding Calculator Guide
This counts molding per wall, which is the only way that produces a number you can actually build with.
A 12×14 room has 52ft of perimeter. Divide by 12ft sticks and you get 5.
You need 6. A 14ft wall cannot be made from a 12ft stick plus a 2ft offcut without a visible joint — so each 14ft wall takes two sticks and wastes 10ft.
Total linear feet is the wrong question. Every wall is its own problem.
The Mistake Most Calculators Make
Dividing perimeter by stock length tells you whether you have enough material. It doesn't tell you whether you have enough usable material.
Molding runs corner to corner in one piece. Leftovers from a long wall are usually too short for any other wall in the room, so they're waste — not inventory. That's why the honest number is higher than the arithmetic, and why people come back from the store one stick short.
Longer Stock Isn't Always Better
Try switching the stock length above and watch the waste figure. With 12ft sticks in a 12×14 room you waste 10ft. With 16ft sticks you waste more per stick but need fewer of them.
There's no universal answer — it depends on your specific wall lengths. What's reliably true is that stock just under your longest wall is the worst case, because every long wall forces a second stick for a few feet.
Cope, Don't Miter, the Inside Corners
Two mitered pieces meeting at an inside corner will open up. Not might — will. Timber moves with humidity and no room is exactly 90°, so a mitered inside corner shows a gap within a season.
A coped joint — one piece square to the wall, the other cut to its profile — closes as the wood moves instead of opening. It takes longer to learn and it's the difference between molding that looks right in year three and molding that doesn't.
Buy Extra, and Buy It Now
Add at least one stick beyond this number. Coping goes wrong while you're learning, the first cut on a spring angle is usually backwards, and profiles get discontinued between visits.
An extra stick is cheap. Matching a discontinued profile is not, and a second trip mid-project on a Sunday afternoon is its own kind of expensive.
Crown Sits at an Angle
This is what makes it hard. Crown isn't flat against the wall or the ceiling — it sits at a spring angle, usually 38° or 45°, which means every cut is a compound cut.
The standard trick is to cut it upside down and backwards in the miter saw, with the fence acting as the wall and the base as the ceiling. It's counterintuitive, and it's worth doing your first cuts on offcuts rather than on the piece you need.
Related: wallpaper calculator, board and batten calculator, lumber calculator.
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