BYTETOOLS

Crown Molding Calculator

Total your crown molding run from a list of wall lengths, get the sticks to buy with a cutting plan, and read the exact compound miter and bevel saw settings.

4
Walls measured
43.00
Total run (ft)
48.16
Order with waste (ft)
4
Sticks to buy
4
Sticks by total length
4
Sticks by optimal cut plan
21.00
Offcut left over (ft)
$11.20
Estimated moulding cost

Compound mitre saw settings

31.62
Inside — mitre flat (°)
33.86
Inside — bevel flat (°)
31.62
Outside — mitre flat (°)
33.86
Outside — bevel flat (°)
45.00
Inside — mitre nested (°)
45.00
Outside — mitre nested (°)
8
Inside corner cuts
0
Outside corner cuts

Cut flat on the table to use the mitre + bevel pair — the moulding lies face up and both saw scales move. Cut nested (upside down against the fence, held at its spring angle by a stop) to use the simple mitre with the bevel at zero. Nested is more accurate on short returns; flat is the only option once the crown is too wide to nest. Inside and outside corners of the same angle share the same settings — what changes is which side of the blade the keeper piece sits on.

The saw settings come from the standard compound-angle geometry, with the turn angle T = 180° − the measured wall angle: mitre = atan(sin S × tan(T ÷ 2)) and bevel = asin(cos S × sin(T ÷ 2)). A 38° spring crown in a square 90° corner gives 31.62° and 33.86°, the pair printed on most saw tables, and a 45° spring crown gives 35.26° and 30.00°. Always cut a scrap test corner first — a wall that reads square against a framing square is often 89° or 91° where it actually matters. Estimates only.

What is the Crown Molding Calculator?

The ByteTools Crown Molding Calculator does the two jobs that trip people up at once. Paste a list of wall lengths and it totals the run, adds your waste allowance, and works out how many sticks you need — both the naive figure and a first-fit cutting plan that tells you when a long wall forces an extra length.

  • Wall-length list with waste allowance, stick count and a first-fit cutting plan
  • Compound miter and bevel for any spring angle and any measured corner
  • Nested (in-position) miter shown alongside the flat-cut pair
  • Warns when a wall is longer than one stick and needs a scarf joint
  • Inside and outside corner counts, plus the number of cuts each needs
  • Copyable cut list; runs entirely in your browser with nothing uploaded

How to use the Crown Molding Calculator

  1. 1

    Pick your length unit and enter the stock length your supplier sells, then paste one wall length per wall into the box, separated by commas or spaces.

  2. 2

    Set the waste allowance and the price per stock length to see the run, the sticks to buy and the estimated cost.

  3. 3

    In the saw panel, choose the crown spring angle (38°, 45°, 52° or a custom value you measured).

  4. 4

    Enter the inside and outside corner angles you measured, and how many of each the room has.

  5. 5

    Read the flat-cut miter and bevel, or the nested miter with the bevel at zero, and copy the whole cut list to your phone.

About the Crown Molding Calculator

The ByteTools Crown Molding Calculator does the two jobs that trip people up at once. Paste a list of wall lengths and it totals the run, adds your waste allowance, and works out how many sticks you need — both the naive figure and a first-fit cutting plan that tells you when a long wall forces an extra length.

Then it solves the saw. Pick a spring angle, enter the corner angle you actually measured, and it returns the miter and bevel for cutting flat on the table plus the simpler miter for cutting nested against the fence. A 38° crown in a square corner comes out at 31.62° and 33.86°, which is the pair stamped on most saw tables.

Everything runs locally in your browser — nothing is uploaded and no measurements leave your device. Treat the output as a starting point: cut a scrap test corner first, because a wall that reads square against a framing square is very often 89° or 91° where it matters.

Frequently asked questions

What are the miter and bevel angles for 38 degree crown molding?

For the common 52/38 crown in a square 90° corner, cut flat on the table with the miter at 31.62° and the bevel at 33.86°. Those are the numbers most saws mark with a crown detent, and the calculator reproduces them exactly when you enter a 38° spring angle and a 90° corner.

What is the spring angle on crown molding?

The spring angle is the angle between the back of the molding and the wall when it sits in place. A 52/38 crown has a 38° spring angle, a 45/45 crown has 45°. If you are not sure, sit an offcut in the corner and measure the angle it makes with the wall.

Should I cut crown molding flat or nested?

Nested — upside down against the fence at its spring angle — needs only a simple miter with the bevel at zero, and it is more accurate on short returns. Cutting flat needs the compound miter and bevel pair but is the only option once the crown is too wide to nest against your saw fence.

Are inside and outside crown corners cut at the same angle?

Yes, for the same corner angle the saw settings are identical. What changes is which side of the blade the keeper piece sits on and which way you swing the saw, so mark the face and the top edge of every piece before cutting.

How much extra crown molding should I buy?

Ten to fifteen percent over the measured run is normal, and this calculator applies that plus a cutting plan that catches walls longer than one stick. A blown miter on the last piece costs far more than one spare length, so round up.

Why do my corners still have a gap at 31.6 and 33.9 degrees?

Because the wall is not square. Measure the actual corner with an angle finder and put that number into the corner-angle field — a single degree of error opens a visible gap on a wide crown. Coping the inside corners instead of mitering them also hides small discrepancies.

Related tools