Flooring Calculator m2: How to Measure Any Room

This flooring calculator works out how many square metres (m²) of flooring you need for a room. You enter the room’s length and width (and optionally the plank or tile size), and it returns the total area, plus the amount to order after adding a waste allowance. It also converts between metres, feet and inches so you can measure in whatever units you have.

Formula

The core formula is simple: Area (m²) = Length (m) × Width (m). For a rectangular room, multiply the two measured sides. The total you should order adds a waste allowance:

Order amount (m²) = Area × (1 + Waste% / 100)

Where:

• Length – the room’s longer side, in metres (or convert feet/inches to metres first).
• Width – the room’s shorter side, in metres.
• Waste% – extra material for cuts, mistakes and pattern matching, usually 5–15%.
• Area – the usable floor surface, in square metres.
• Order amount – the actual quantity to buy, in square metres.

Worked Example

Using the default values: a room 5 m long and 4 m wide, with a 10% waste allowance.

1. Area = 5 × 4 = 20 m²
2. Waste = 20 × 10 / 100 = 2 m²
3. Order amount = 20 + 2 = 22 m²

So for a 20 m² room, you should buy 22 m² of flooring. This matches the calculator’s output.

Why You Need a Waste Allowance

No room is a perfect rectangle, and no installation is perfect. You will need to cut planks or tiles to fit around doorways, corners, pipes and alcoves. Some cuts will be wrong, and you may need to replace a damaged plank later. A 10% allowance is standard for straight layouts; diagonal layouts or patterned tiles (like herringbone) need 15% because more cutting is involved. For a small room with many obstructions, err on the higher side.

How to Measure an Irregular Room

Most rooms are not simple rectangles. For L-shaped or U-shaped rooms, split the floor into rectangles, calculate each area, then add them together. For example, an L-shaped kitchen might be a 4 m × 3 m section plus a 2 m × 2 m section: that’s 12 + 4 = 16 m². For triangular sections, use (base × height) / 2. For curved walls, approximate with straight lines – you will order extra anyway.

Common Mistakes and How to Avoid Them

• Mixing units – always convert feet and inches to metres before multiplying. 1 foot = 0.3048 m; 1 inch = 0.0254 m.
• Forgetting the waste – ordering exactly the measured area leaves no room for errors.
• Measuring at skirting boards – measure from wall to wall, not from skirting to skirting, which gives a smaller area.
• Rounding too early – if you round each measurement to the nearest 10 cm, you can lose or gain a significant amount over a large room.
• Ignoring the direction of planks – if you lay planks across a room, you may need extra for the final row.

How to Convert Square Feet to Square Metres

If your room measurements are in feet, the area comes out in square feet. To convert to square metres, multiply by 0.092903. For example, a 10 ft × 12 ft room is 120 sq ft, which equals 120 × 0.092903 = 11.15 m². Most online calculators and this one do the conversion for you if you enter feet, but it’s useful to know the factor when checking manually.

What About the Number of Packs or Boxes?

Flooring is sold in packs, and each pack covers a specific area – often printed on the box (e.g., 2.5 m² per pack). Once you have your order amount in m², divide by the pack coverage and round up to the nearest whole pack. For 22 m² with 2.5 m² per pack, you need 22 / 2.5 = 8.8, so you buy 9 packs. This is a separate step from the area calculation, but essential when actually purchasing.

Frequently Asked Questions

How do I measure a room for flooring in metres?

Use a tape measure to find the length and width of the room at its widest points, from wall to wall. Write down the measurements in metres (or convert from feet/inches). Multiply the two numbers to get the area in square metres. Add 10% for waste, then round up to the nearest pack size.

What is the difference between m² and sq ft?

Both measure area, but in different units. 1 square metre equals 10.7639 square feet. To convert m² to sq ft, multiply by 10.7639. To convert sq ft to m², multiply by 0.092903. Many product specifications list both, but it’s easy to mix them up – always double-check which unit you’re using.

How much extra flooring should I buy?

For straight plank or tile layouts, buy 10% extra. For diagonal layouts, herringbone patterns, or rooms with many corners and cutouts, buy 15%. If you expect to replace damaged planks later, consider buying a few extra packs and storing them – but note that dye lots can vary, so matching later is not guaranteed.

Can I use this calculator for carpet, vinyl, or laminate?

Yes, the area calculation is the same for any type of flooring. However, carpet often comes in rolls of fixed width (e.g., 4 m or 5 m), so you may need to order based on the roll width, not just the area. Laminate and vinyl planks are usually sold by pack coverage, so the m² calculation works directly.

What if my room is not a perfect rectangle?

Split the room into rectangles (and triangles if needed), calculate each area separately, then add them together. This gives a good approximation. Always add a slightly higher waste allowance (12–15%) for irregular shapes to cover the extra cutting.

Does the calculator account for doorways and alcoves?

No, the calculator assumes a simple rectangle. For doorways, you typically do not need to subtract the gap because the flooring should extend into the doorway for a clean transition. For alcoves, measure them as part of the rectangle – it’s safer to overestimate slightly.

Related

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• Drywall Adhesive Calculator: How Much You Need
• Drywall Board Calculator: Sheets & Cost

in length | Room length | m | 5 | 0
in width | Room width | m | 4 | 0
in waste | Waste allowance | % | 10 | 0
out area | Floor area | m² | length * width | 2
out order | Flooring to order | m² | area * (1 + waste / 100) | 2