Method / assumptions / examples
How this calculation works
The result is deterministic: the same measurements always return the same estimate. Here is the relationship and where real-world results can differ.
Formula
Area = polygon shoelace area; Packages = ceil((net area × (1 + waste %)) ÷ package coverage)
The room outline is represented as a measured polygon. Its area is calculated with the shoelace formula and its perimeter is the sum of all wall segments. Any deduction is removed before the waste allowance, then package count is rounded up to a whole purchasable unit.
Worked example
Examples
The room covers 120 ft² with 44 linear feet of perimeter. At 10% waste and 20 ft² per box, order 7 boxes.
A 12 × 10 ft outer footprint with a 7 × 6 ft corner removed covers 78 ft² while retaining a 44 ft measured perimeter.
Common mistakes
What to check before using the result
- Start with a rectangle or L-shape, then add a corner anywhere the wall changes direction. Drag it into place or type exact X and Y coordinates.
- Use the deduction only for permanent areas that will not receive material, such as a large built-in or open void.
- Waste depends on pattern, room shape, plank or tile format, matching requirements, and installer method. Verify the package coverage printed on the product.
FAQ
Frequently asked questions
How do I draw an irregular room?
Start from the closest preset, choose a plus point on an edge to insert another corner, then drag the vertex or enter its exact coordinates. Keep the outline from crossing itself.
Can I measure in metres?
Yes. Switch the room workspace to metric and the outline, coordinates, deductions, and package coverage convert together. Waste percentage and package price do not change.
How much waste should I add?
Ten percent is a common starting point for straightforward flooring layouts. Complex angles, diagonal patterns, large-format tile, matching, and future repair stock can require more.
Why does the calculator round packages up?
Flooring, tile, panels, and similar materials are normally sold as whole boxes or packs. A fractional package is not purchasable, so the estimate rounds upward.
Can I use the perimeter for baseboard?
Yes, as a starting estimate. Subtract door openings if appropriate and add a cutting allowance based on the stock lengths you plan to buy.