Crown Molding Calculator

How to Calculate Crown Molding

The math is simple but the waste factor matters a lot. Start with the room perimeter: 2 × (length + width). For a 12 × 14 ft room, perimeter = 52 ft. If the crown molding stops at each door opening, subtract the total width of openings (usually 3 ft per standard interior door). Add 10-15% waste for miter cuts, corners, and culls. Divide by your chosen stick length and round up. For 52 ft with 10% waste and 12 ft sticks: 52 × 1.10 ÷ 12 = 4.77 → 5 sticks.

Stick Length Strategy

The shorter your sticks, the more joints you'll have, and the more waste you'll generate from cutoffs. On a 14 ft wall with 10 ft sticks, you have to join two pieces mid-wall; with a 14 ft stick, one piece covers it. Try to buy long enough sticks that each wall is covered by one continuous piece. In small rooms (under 8 ft per wall), 8-footers work fine. In typical living rooms, 12 ft is the sweet spot. For great rooms and open-plan spaces, 14 or 16 ft sticks are worth the extra handling.

Inside Corners and Coping

Crown molding professionals cope inside corners rather than mitering them. The cope cut follows the exact profile of the adjoining piece so they mate perfectly even when the wall isn't perfectly 90°. Plan your stick layout so you cope one end and leave the other end square (to be coped against by the next piece). This means every stick is cut once with a cope and once square — not both ends mitered.

Outside Corners

Outside corners are always 45° miters. Cut both mating sticks with opposing 45s so they form a clean 90° outside angle. Outside corners waste a bit more material because you can't use the mitered-off end. Account for this in your waste factor — rooms with multiple outside corners need 15-20% waste.

Common Room → Crown Molding Reference

Linear feet and stick count (with 10% waste) for typical room sizes:

Frequently Asked Questions

Should I run crown over doors?

Yes — continuous crown around the room looks cleaner. Only stop at doors if there is no head room above them.

What spring angle of crown should I use?

38° or 45° spring angle — check before buying. Different spring angles need different miter saw settings and have different coverage.

Can I use MDF crown molding?

Yes — MDF is cheaper and paint-ready. Pine is easier to cope. Hardwood (oak, maple) is for stain-grade finishes.

Do I need to buy extra sticks for cutoffs?

The waste factor covers cutoffs. If you're new to coping, buy one extra stick as a practice/mistake buffer.

How do I measure a room with many corners?

Perimeter still equals the sum of all wall lengths — just add them up one by one. The calculator handles rectangular rooms; for L-shaped or complex rooms, sum the wall lengths manually and enter half the total as length and half as width.