Floor Area Calculator
Flooring, carpet and tiling are sold by area, and the number you need is the room’s floor area plus a wastage allowance for cuts and offcuts. This calculator takes the room’s length and width, returns the area in both square metres and square feet, and adds the wastage percentage you choose so you buy the right amount of material.
Enter the room length and width and pick the unit (metres or feet). The calculator returns the plain area, the area with wastage (10% is typical for flooring), and both metric and imperial equivalents so you can order in whichever unit the supplier uses. For multiple rooms, calculate each and add the totals.
It is the calculation behind every flooring, carpet or tiling purchase — the room’s area in both metric and imperial, with a wastage allowance, so you order in whichever unit the supplier uses without a second conversion.
Enter your values to see the result.
How this is calculated
The floor area is length × width, with both dimensions converted to metres first (feet × 0.3048). The result is shown in square metres and converted to square feet by dividing by 0.092903, the square-metres-per-square-foot factor, so you can order in whichever unit the supplier uses. A wastage percentage is added on top — 10% is standard for flooring and carpet, 15% for diagonal or patterned layouts — and the with-wastage area is shown in both units.
The wastage allowance covers cuts at the edges, offcuts around doorways and alcoves, and the inevitable mistakes. For wide planks or large-format tiles, where each cut wastes more material, lean toward 15%. For carpet, which is sold in fixed widths and may need the room dimension rounded up to the roll width, the wastage also covers the join — a carpet supplier will often calculate this differently, so use this figure as a planning estimate and confirm with the supplier.
The model assumes a single rectangular room. For multiple rooms, calculate each separately and add the areas, including each room’s wastage, rather than averaging dimensions — mixing rooms in one calculation hides where the waste falls. For irregular rooms (L-shapes, bays), break the floor into rectangles, calculate each, and sum. The unit toggle lets you enter feet for a US supplier and still read the m² figure, or vice versa.
Worked example
A 5 m × 4 m room, 10% wastage, ordering in m².
- 1Area = 5 × 4 = 20 m².
- 2In square feet = 20 ÷ 0.092903 = 215.3 ft².
- 3With 10% waste = 22 m² (236.8 ft²).
- 4Order 22 m² of flooring to allow for cuts.
Frequently asked questions
- How much wastage should I allow for flooring?
- 10% for a straightforward rectangular room with a standard layout, 15% for diagonal layouts, wide planks or rooms with many corners and alcoves. Carpet usually allows 10%, tiles 10–15%.
- Can I calculate multiple rooms at once?
- Calculate each room separately and add the areas together, including each room’s wastage. Mixing rooms in one calculation hides where the waste falls, so per-room is clearer.
- Why show both m² and ft²?
- Because flooring is sold in both: carpet and laminate in Europe by the m², in the US by the square foot or square yard. The calculator gives both so you can order in the unit your supplier uses without a second conversion.
- How do I handle an L-shaped room?
- Split the L into two rectangles, calculate each with this tool, and add the two areas (including each one’s wastage). Trying to average the dimensions of an L-shape in one calculation understates the area and the cuts, so per-rectangle is more accurate.
- Why show both m² and ft²?
- Because flooring is sold in both: carpet and laminate in Europe by the m², in the US by the square foot or square yard (9 ft²). Showing both lets you order in the unit your supplier uses without a separate conversion, and the unit toggle lets you enter the room in feet and still read the metric figure.
Related calculators
Method: area = length × width (converted to metres); square feet = m² ÷ 0.092903; wastage added as a percentage. Last updated: September 2026.
These results are general estimates from established formulas and conversion factors. Paint coverage, tile yields, concrete volumes, fuel economy, oven behaviour and clothing and shoe sizes vary by product, surface, vehicle, oven and brand. Always confirm with your supplier, the product label or the brand’s own size chart before buying or acting on a calculation.