Crown Molding Length Calculator
Enter the ceiling perimeter in meters and a waste percentage for cuts and corners to get the linear meters to buy: total = perimeter × (1 + loss/100).
Metros lineares
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Ceiling moulding (cornice) calculation
Linear meters = ceiling perimeter + 5% waste, the extra covering the 45° miter cuts you make at each corner. Take a 4 × 3 m room: 2 × (4 + 3) = 14 m, and 5% on top gives you 14.7 m. As for what to buy, the simple straight profile is modern and runs 3–5 cm wide. The Versailles decorative one has a classic carved profile. EPS foam is the cheap and light option at R$ 5–10/m, plaster is the classic look at R$ 15–30/m and gets painted in place, and polyurethane (Orac Decor) is durable, handles moisture and costs R$ 50+/m. Bars ship in 2.00 m lengths for EPS and polyurethane, or 1.20–1.50 m for plaster. If you want cove lighting, pick a moulding with an integrated upper channel and pull it 10–15 cm off the wall so the LED strip stays hidden.
Applications and standards
People reach for it as a classic architectural finish, to hide ceiling imperfections where the ceiling meets the wall (cracks, uneven plaster), and to run indirect cove lighting with hidden LED. You see it in hotel halls, classic interiors and neoclassical living rooms. Plaster mouldings go up with plaster paste; EPS and polyurethane use PU adhesive or a specific contact glue. Paint it the same colour as the ceiling for visual continuity, or go for contrast if you want the profile to stand out.
FAQ
EPS or plaster? EPS is lighter and you can install it yourself, but it burns easily and looks plasticky from up close. Plaster weighs more and needs a skilled installer, though the finish is far nicer. Go with plaster for living rooms and high ceilings.
Do I need to cut 45° miters? Yes, at every internal and external corner. A miter box or coping saw does the job. For EPS there are pre-cut external corner pieces that save you the trouble.
Does it work with drywall ceiling? It does, as long as you stick to lighter mouldings (EPS or polyurethane) and glue them. Don't screw heavy plaster mouldings into a drywall ceiling unless there's metal-frame reinforcement behind it.
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The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.