Crown Moulding Calculator
Estimate crown moulding stock from a room perimeter or measured total run.
Last reviewed September 19, 2026
Result
Buy 4 piecesEstimate
No extra is added by default. Use Custom for mitres, scarf joints, pattern matching and unusable short offcuts.
- Length to order, allowance included
- 54 ftEstimate
- Measured moulding run
- 54 ft
https://calcgallery.com/lumber-carpentry/crown-moulding-calculator/
Results are estimates for planning only. Actual needs vary with site conditions, products and workmanship. Always confirm quantities with your supplier and follow local building codes and manufacturer instructions. Read the full disclaimer
How to use it
- Enter rectangular room dimensions, or switch to a measured total run.
- Enter the stock piece length available from your supplier.
- Add a custom allowance for mitres, scarf joints and unusable offcuts.
- Read the total run, order length and whole stock-piece quantity.
How it is calculated
For a rectangular room, the measured run is the perimeter. A directly measured run can be used for irregular spaces:
Room run = 2 × (length + width)
Order length = run × (1 + allowance)
Pieces = ceil(order length ÷ stock piece length)The result assumes useful offcuts can move to another wall.
Planning cuts
Make a wall-by-wall cut list. The total is useful for budgeting, but a cut list shows whether each long wall can be made from available stock and where a scarf joint must land.
Check pattern direction. Ornamental profiles may have a repeating motif or a clear top and bottom. Reversing an offcut can make it unusable.
Measure at installation height. Walls can vary between floor and ceiling. Measure the actual crown line rather than relying only on floor dimensions.
Practice compound cuts. Crown spring angle and corner angle affect saw settings. Follow the profile manufacturer’s installation method.
With your numbers
- Measured run = 54 ft
- With 0% cutting allowance = 54 ft
- That length ÷ 16 ft stock, rounded up to 4 pieces
Quick reference
No extra is added by default. Use Custom for mitres, scarf joints, pattern matching and unusable short offcuts.
| Job | Stock pieces to buy |
|---|---|
| 10 × 12 ft room, 16 ft stock | 3 |
| 12 × 15 ft room, 16 ft stock | 4 |
| 15 × 20 ft room, 16 ft stock | 5 |
| 80 ft measured run | 5 |
| 3 × 4 m room, 4.8 m stock | 3 |
| 24 m measured run | 5 |
Common questions
- How much crown moulding for a 12 by 15 foot room?
- The perimeter is 54 ft. With 10% extra, the order length is 59.4 ft, which is 4 pieces when stock is 16 ft long.
- Does the calculator subtract doors and windows?
- No. Crown moulding normally runs continuously at the wall-to-ceiling junction, above ordinary doors and windows.
- Are offcuts always reusable?
- No. This is a total-length estimate. Mitre direction, scarf placement, pattern matching and a minimum useful length can make another stock piece necessary.
- Is crown measured along the wall or its angled face?
- Measure the room run along the wall. Use the stock length printed for the moulding, not its face projection or spring angle.