Crown Molding Calculator

Calculate linear feet, pieces to purchase, miter & bevel angles, and total cost for your crown molding project — across multiple rooms.

Rooms

Waste Factor

Molding Sold In

$ /LF
ft
Total Linear Feet Needed
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including 15% waste
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Rooms
—
Perimeter LF
—
Pieces to Buy
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Cost Estimate

LF Per Room

Linear feet contribution of each room (perimeter, before waste).

Crown Molding Miter & Bevel Cut Reference

Crown molding has a spring angle — the angle at which it sits against the wall. This angle determines the correct miter and bevel settings on your saw.

Spring Angle Miter Angle Bevel Angle Common Use
38° 31.62° 33.86° Standard MDF / wood profiles
45° 35.26° 30.00° Foam & polyurethane crown
52° 38.07° 26.34° Steep / wide profiles

Inside Corners

For inside (90°) corners, one piece is cut square and the second piece is coped to fit — OR both pieces get compound miter/bevel cuts. Coping produces a tighter fit as walls settle. Miter angle = same value as table above; bevel direction is reversed for the two sides.

Outside Corners

Outside corners require compound cuts on both pieces. Use the miter and bevel values in the table, mirroring the bevel direction for left and right cuts. Outside corners are more visible — a tight fit here matters most. Pre-finish or prime before installation.

Saw Flat Method (Compound Miter Saw)

Lay the molding flat on the saw table with the wall face down. Set miter to the table-above angle and bevel to the table angle from the chart. This avoids needing a tall fence. Alternatively, stand the molding at the spring angle against the fence — then use 45° miter with 0° bevel for 90° corners.

Finding the Spring Angle

Hold the molding in position against a wall and ceiling. The angle it makes with the wall is the spring angle. Most profiles are 38° or 45°. Polyurethane foam moldings are almost always 45°. When in doubt, check the manufacturer's spec sheet.

Crown Molding Buying Guide

Tips for measuring, buying, and installing crown molding like a pro.

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How to Measure

  • Measure each wall from corner to corner at ceiling height.
  • Add all wall lengths to get the room perimeter.
  • Add 15–20% waste for miter cuts — higher for rooms with many corners.
  • For bay windows or irregular rooms, measure each run individually.
  • Always round up to the nearest piece length when ordering.
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Types of Crown Molding

  • MDF: Cheapest, paints well, no grain — best for painted rooms.
  • Solid Wood (pine/poplar): Can be stained or painted. Heavier, more expensive. Prone to minor movement with humidity.
  • Polyurethane Foam: Lightweight, moisture-resistant, easiest to install. Best for kitchens, bathrooms. Not suitable for staining.
  • PVC / Composite: Excellent for exterior soffits or humid interiors. Very durable.
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Installation Tips

  • Locate and mark wall studs and ceiling joists before installing.
  • Nail into studs (not just drywall) for a secure hold.
  • Start with the wall opposite the main entry for best visual alignment.
  • Use a caulking gun to fill gaps at the wall and ceiling interface.
  • For outside corners, cut test pieces in scrap first.
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Finishing & Caulk vs. Putty

  • Prime before painting — unpainted MDF swells if painted directly with latex. Use an oil-based primer or shellac sealer first.
  • Caulk gaps at the ceiling and wall: paintable acrylic latex caulk fills movement gaps better than wood putty.
  • Nail holes: Fill with spackling compound or wood putty after priming, then sand smooth before the final coat.
  • Two finish coats of semi-gloss or satin paint gives the best durability.
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Piece Length Selection

  • 12 ft is the most common stock length — fits most rooms with one or two joints per wall.
  • 16 ft lengths reduce joints in large rooms but are harder to transport and handle alone.
  • 8 ft lengths are convenient for small rooms or repairs; more joints required in larger rooms.
  • Minimize butt joints (lengthwise splices) — they show more than corner cuts. Plan runs to avoid mid-wall joints where possible.
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Shopping Checklist

  • Crown molding (LF from this calculator)
  • Primer (oil-based for MDF)
  • Finish paint (semi-gloss or satin, same color as ceiling or contrast)
  • Paintable caulk + caulk gun
  • Wood putty or spackling for nail holes
  • Finish nails (2" for most profiles) + nail gun or hammer
  • Miter saw with compound bevel capability
  • Stud finder, measuring tape, pencil

How to Use This Calculator

  1. Add your rooms — Enter each room's name, length, and width. Check or uncheck rooms to include or exclude them from the total.
  2. Choose waste factor — 15% is recommended for rooms with many miter cuts. Use 10% for simple rectangular rooms, 20% for complex layouts or beginners.
  3. Select molding length — Choose the stick length sold at your local store (8, 12, or 16 ft).
  4. Enter price per LF — Check your local lumber yard or home center for current pricing.
  5. Review the Room List tab — See a visual comparison of how much molding each room needs.
  6. Check Miter Angles tab — Get the exact compound miter and bevel settings for your spring angle before you start cutting.

Key Formulas

Perimeter = 2 × (Length + Width)
With Waste = Total LF × (1 + Waste %)
Pieces = ⌈With Waste ÷ Piece Length⌉
Total Purchased = Pieces × Piece Length
Cost = Total Purchased × Price per LF
Waste LF = Total Purchased − With Waste

Crown Molding Glossary

Spring AngleThe angle at which crown molding sits between the wall and ceiling. Common values: 38°, 45°, 52°.
Miter AngleThe horizontal rotation of the saw blade when making a compound cut for crown molding corners.
Bevel AngleThe tilt of the saw blade from vertical when making a compound cut.
Coped JointA joint where one piece is cut to follow the profile of the other — used for inside corners for a tighter fit.
Butt JointA simple end-to-end splice in the middle of a wall run; minimized by using longer piece lengths.
Linear Foot (LF)A measurement of length — one linear foot equals 12 inches. Crown molding is sold and estimated per linear foot.
Waste FactorExtra material added to account for miter cut waste, measurement errors, and damaged pieces.
Compound Miter SawA saw that can cut at both a miter angle and a bevel angle simultaneously — required for crown molding cut with the piece lying flat.

Frequently Asked Questions

How much waste should I add for crown molding?

15% is the standard recommendation for crown molding because every corner requires a miter cut that wastes a few inches of material. Simple rectangular rooms with 4 inside corners can use 10%. Rooms with bay windows, tray ceilings, or many outside corners should use 20%. It is always better to have extra than to run short mid-project.

What is the spring angle and how do I find it?

The spring angle is the angle the molding makes against the wall when installed. Hold a piece of molding in the corner between the wall and ceiling as it will be installed, then measure the angle between the back of the molding and the wall. Common values are 38° (standard wood/MDF), 45° (foam/polyurethane), or 52° (wide or steep profiles). The manufacturer's spec sheet will also list it.

Can I install crown molding without a compound miter saw?

Yes. The traditional method is to stand the molding at its spring angle against the fence of a standard miter saw. In this position, a simple 45° miter (with 0° bevel) will cut a perfect inside corner for a 90° room. This avoids compound cuts but requires a tall fence or careful support to hold the molding at the correct angle during the cut.

What is a coped joint and when should I use it?

A coped joint is where one piece is cut square against the starting wall and the adjacent piece is cut to follow the profile of the first piece using a coping saw or jigsaw. Coped joints are preferred for inside corners because they accommodate walls that are not perfectly square and close up better when wood expands and contracts with humidity changes. Miter joints at inside corners can open up over time.

Should I paint crown molding before or after installing it?

It is easier to prime and apply the first coat of paint before installation, then touch up the nail holes and caulk lines after. This way you only need to cut in along the ceiling and wall edges rather than painting the entire profile in place. Always prime MDF molding with an oil-based primer before any latex coats to prevent swelling.

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