Crown Molding Calculator
Linear feet and miter angles for rooms with corners.
About this calculator
This calculator does two separate jobs: it figures out how much crown molding to buy from the room's perimeter, and it computes the compound miter and bevel saw settings for cutting inside corners at your chosen spring angle. Room perimeter, Linear ft, and Pieces to buy are unaffected by the spring angle entirely -- they come purely from room dimensions, waste factor, and board length -- while Miter angle and Bevel angle depend only on the spring angle, not on room size at all. As spring angle increases across its full 1-90 degree range, the miter angle setting rises while the bevel angle setting falls -- they move in opposite directions, which is why compound crown cuts need two separate saw settings rather than one.
At the common 38-degree "38/52" spring angle, that works out to roughly a 31.6-degree miter and a 33.9-degree bevel; at a 45-degree "45/45" spring angle, it's exactly 35.26 degrees miter and 30 degrees bevel -- the two best-known reference pairs in the trim carpentry trade, and useful checks against your own saw's printed angle scale. Unlike baseboard, crown molding is assumed to run continuously through door openings (it sits near the ceiling, above the door), so this calculator does not deduct for doors the way a baseboard or chair rail calculator would.
Inputs
Results
Room perimeter (ft)
52
How to Use This Calculator
- Enter Room length (ft), Room width (ft), and Spring angle (°).
- Set Cost per linear ft ($), Waste factor (%), and Piece length (ft).
- Review the Room perimeter (ft) result.
- Use Linear ft (with waste) and Pieces to buy to inform your decision.
How the result changes with Room length (ft)
| Room length (ft) | Room perimeter (ft) |
|---|---|
| 7 | 38 |
| 11 | 46 |
| 21 | 66 |
| 35 | 94 |
What each input means
- Room length (ft)
- Length of the room in feet.
- Room width (ft)
- Width of the room in feet.
- Spring angle (°)
- Angle the crown sits off the wall. Common values: 38° (38/52 crown) or 45° (45/45 crown).
- Cost per linear ft ($)
- Price per linear foot of crown molding.
- Waste factor (%)
- Extra material for mitered cuts and waste.
- Piece length (ft)
- Length of each crown molding piece you will purchase.
What each result means
- Room perimeter (ft)
- Total ceiling perimeter requiring crown molding.
- Linear ft (with waste)
- Total footage including waste factor.
- Pieces to buy
- Number of full-length pieces to purchase.
- Miter angle (°)
- Saw miter setting for 90° inside corners at your spring angle.
- Bevel angle (°)
- Saw bevel setting for 90° inside corners at your spring angle.
- Scarf joints
- Mid-wall splice joints needed where walls exceed board length.
- Material cost
- Estimated cost for crown molding material.
- Total Cuts
- Miter cuts at the 4 inside corners plus two cuts per scarf joint.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersRoom length (ft) = 14, Room width (ft) = 12, Spring angle (°) = 38, Cost per linear ft ($) = 3 = 6 input(s) provided
- Calculate Room perimeterRoom perimeter = 2 * (roomLength + roomWidth)52 = 52
- Calculate Linear ftLinear ft = perimeter * (1 + wastePct / 100)57.2 = 57.2
- Calculate Pieces to buyPieces to buy8 = 8
Engine last updated . Checked against 2 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
Does the spring angle affect how much crown molding I need to buy?
No -- Room perimeter (ft), Linear ft (with waste), and Pieces to buy come entirely from room dimensions, Waste factor (%), and Piece length (ft). Spring angle (deg) only feeds Miter angle and Bevel angle, the saw settings for cutting corners -- it has no effect on the quantity of molding needed.
Why do the miter and bevel angles move in opposite directions as spring angle changes?
As Spring angle (deg) rises from a shallow angle toward 90 degrees, Miter angle increases while Bevel angle decreases -- across the full declared range this never reverses. That's a geometric consequence of how a crown profile's tilt off the wall trades off between the two saw axes for the same 90-degree inside corner.
What miter and bevel should I expect for a standard 38-degree spring angle?
A 38-degree spring angle (the common "38/52" crown profile) works out to roughly a 31.6-degree miter and a 33.9-degree bevel for a 90-degree inside corner. These are widely published reference values in trim carpentry -- check them against your saw's own angle scale before cutting.
Does crown molding get deducted at doorways like baseboard does?
No -- this calculator assumes crown molding runs continuously around the room, since it sits at the ceiling line above door openings rather than at floor level where a door interrupts the run. Room perimeter (ft) is not reduced for doorways the way a baseboard or chair rail calculator's linear footage would be.
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