Crown Molding Calculator

Measure each wall where the crown meets the ceiling. Add the wall lengths to get linear feet. Add 10 percent for a room with four corners or fewer, or 15 percent for more. Divide by the stick length and round up. A 14 by 12 foot room has 52 feet and needs 57.2 feet, which is 8 sticks of 8 feet.

1. Measure each wall at the ceiling line, corner to corner.
2. Add the walls. Convert inches to feet by dividing by 12.
3. Count the corners. Pick 10 percent waste for four or fewer and 15 percent for more.
4. Multiply the total by one plus the waste. Divide by the stick length and round up.
5. Check the cut plan. Leftover pieces from one wall can fill the next.

To get wall lengths from a floor plan, use our square footage calculator. It handles odd room shapes and gives you the perimeter.

The four walls measure 14, 12, 14 and 12 feet. They add to 52 feet. Four corners give a 10 percent allowance, so the order is 57.2 feet. Eight foot sticks give 8 by simple division. A cut plan needs 7, because the four leftover pieces share 3 sticks. Buy 8 so a miscut does not stop the job.

Each wall needs one full 8 foot stick plus a short piece, so the room has 4 scarf joints. A scarf joint is an angled splice, glued and nailed over a stud.

Every corner adds two angled cuts and a chance to miscut. DIYProject.ai uses 10 percent for a simple room and 15 percent for many corners. This calculator uses 10 percent up to four corners and 15 percent above four. The six-wall room with one outside corner has six corners, so it gets 15 percent: 52 feet becomes 59.8.

The two percent figures are practitioner guidance, not a controlled study. The limit of four corners is our own rule. Decorative Ceiling Tiles adds 15 percent to every job, and Inch Calculator adds one foot. Type your own percent if your trim carpenter uses a different one.

Longer sticks mean fewer joints. The 14 by 12 foot room needs 8 sticks of 8 feet with 4 joints, 5 sticks of 12 feet with 2 joints, or 4 sticks of 16 feet with none. Rounding each wall up on its own would buy 8, 6 and 4. Packing the leftovers avoids the extra pieces.

Stores stock different lengths. Inch Calculator says molding is generally sold in 8 foot lengths. Check yours before you plan, or type a custom length from 4 to 20 feet.

For crown cut flat on the saw table, miter equals atan(sin S / tan(C/2)) and bevel equals asin(cos S x cos(C/2)). S is the spring angle and C is the wall corner. For 38 degree crown at 90 degrees, that is a 31.6 degree miter and a 33.9 degree bevel. The 45 degree spring gives 35.3 and 30.0.

Table cells read miter / bevel in degrees. Many walls are not exactly square, so measure the corner and use the calculator's corner field. Blocklayer advises cutting test pieces from scrap first.

Flat cuts use a miter and a bevel with the broad back on the saw table. Nested cuts hold the crown upright against the fence, and need a miter of 90 minus half the wall corner with no bevel. Both work. The table above applies to the flat method only.

On an inside corner the top of the molding is shorter. On an outside corner the bottom is shorter (Blocklayer). Outside corners use the same angles with the two pieces swapped.

Measure each wall at the ceiling line, not along the floor. Walls are rarely the same length top and bottom. Add each section of a jog or bump-out as its own wall, and count its corners.

• Use wall-by-wall mode for any room that is not a plain rectangle.
• Corners that point into the room are outside corners. A bump-out adds one or more.
• Crown usually runs over doors and windows, so do not subtract them. Leave out only the wall length where no crown will go, such as above full-height cabinets.
• The six-wall example, with walls of 14, 12, 12, 2, 2 and 10 feet, adds to 52 feet and needs 5 sticks of 12 feet with 1 joint, or 8 sticks of 8 feet.
• DIYProject.ai says to add a foot for each outside corner. Its own worked example does not. This calculator relies on the waste allowance instead.

For the walls themselves, see the paint calculator and the drywall calculator.

This page counts crown molding length, sticks and saw angles. It does not choose a crown size for your ceiling height, give an installed price per foot, or teach coping. It does not cover curved walls, and it has no metric input yet. Prices appear only if you type a price per stick. The results are planning quantities for reference. Measure the walls on site and consult your supplier on stick lengths and counts before you order.

For wall color, use the paint calculator. For wall covering, use the wallpaper calculator. For the floor, use the flooring calculator.

Published October 2026. Last updated October 2026. Next review October 2027.

Sarah Kim, CPECPE

Reviews: cost calculators · 24 calculators reviewed

Sarah Kim is a Certified Professional Estimator (CPE) with 15 years of construction cost estimation experience. She holds CPE certification from ASPE (member #20-4891). At Turner Construction, she managed material cost analysis on commercial projects ranging from $2M to $45M. At CalcSummit, she writes and verifies all cost estimation and interior finish calculators, updating regional cost benchmarks quarterly using RS Means-informed data.

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