How this flooring calculator works
Flooring is sold by the box and estimated by floor area. The calculator takes the floor as length × width (or a known area), adds the waste allowance you choose, divides by the coverage printed on the box and rounds up. It shows the estimated consumption and the purchased area separately so you can see how much is leftover.
The formula
purchase basis = net floor area × (1 + waste %)
boxes = ⌈ purchase basis ÷ coverage per box ⌉
Worked example
- Floor 12 × 12 ft = 144 sq ft
- 10% waste → 158.4 sq ft purchase basis
- Boxes of 23.77 sq ft: 158.4 ÷ 23.77 = 6.66 → 7 boxes = 166.39 sq ft purchased, about 22 sq ft leftover
Typical box coverage
| Product | Coverage per box (varies by line) |
|---|---|
| Luxury vinyl plank (LVP) | 18–24 sq ft |
| Laminate | 18–24 sq ft · 1.5–2.5 m² |
| Engineered hardwood | 15–30 sq ft |
| Porcelain / ceramic tile | 8–15 sq ft |
Box coverage differs between lines of the same product, so always use the number on the box you intend to buy — choose "Enter from my product label" above.
Measuring tips
- Measure the floor at the widest points, wall to wall, under any trim that will come off.
- L-shaped rooms: split into rectangles, calculate each and add the areas, or enter the known total area.
- Closets and doorways that get the same flooring are additional floor surfaces in the planner.
Scope and limits
The calculator assumes a straight lay. It does not optimise plank layout, check subfloor suitability, or include underlayment, transitions, baseboard or adhesive. Diagonal, herringbone and pattern-matched layouts need a reviewed, higher allowance.
How to calculate flooring boxes
- Measure the floor length and width (or enter a known floor area after exclusions).
- Choose your product or enter the coverage per box from the label.
- Review the waste allowance — 10% for a simple straight lay; more for diagonal, herringbone or complex rooms.
- Read the purchase basis, box count and the area you will actually buy.
- Carry the room into the planner to combine flooring with paint and drywall on one list.
Frequently asked questions
How many boxes of flooring do I need for a 12 × 12 room?
144 sq ft of floor plus 10% waste is 158.4 sq ft. With boxes of 23.77 sq ft that is 158.4 ÷ 23.77 = 6.66, rounded up to 7 boxes (166.39 sq ft purchased). Boxes of 20 sq ft would need 8.
What waste allowance should I use for flooring?
10% is a common planning figure for a straight lay in a simple rectangular room and is prefilled as an editable assumption. Diagonal layouts, herringbone, rooms with many jogs, and planks with grain or pattern matching usually need more — 15% or above — and should use a figure your installer or the manufacturer recommends.
Do doors and windows reduce the flooring area?
No. Wall openings never affect the floor. A built-in island, a fireplace hearth or a fixed cabinet run that will not be floored is a floor exclusion, entered as its own length × width in the room planner.
Does the calculator include underlayment or trim?
Not automatically. Underlayment has its own coverage and overlap rules, and baseboard needs a perimeter model with door deductions — reusing floor area for either would be wrong. Add them as manual items in the planner for now.
Should I round boxes up per room or for the whole house?
If the same product goes in several rooms and you are happy to carry offcuts between them, pooling the purchase rounds once and can save a box or two. The planner offers both and shows the difference.