Home & Construction⏱ 5 min read
How to Calculate How Much Flooring You Need for Any Room
Buying too little flooring means a second trip that might result in a batch mismatch. Buying too much wastes money. Here's the exact calculation for every floor type — including stairs.
Flooring calculations seem straightforward but consistently catch people out — especially with plank-direction constraints, pattern matches, and rooms that aren't perfect rectangles. Here's the complete guide.
The Basic Calculation
Area = Room length x Room width (in metres)
Add 10% for waste and cuts: Area x 1.10
Example: 4.2m x 3.6m room
Area = 15.12 m2
With 10% waste: 15.12 x 1.10 = 16.63 m2
Order: 17 m2
Waste Percentage by Flooring Type
Floor TypeRecommended WasteReason
Luxury vinyl plank (LVP)8-10%Click-lock cuts are straightforward
Laminate (straight lay)10%End cuts needed every row
Laminate (diagonal lay)15%Diagonal cuts waste more material
Solid wood (tongue and groove)10-12%Acclimatisation rejects plus cuts
Carpet (from roll)10-15%Roll width may not match room width
Patterned carpet15-20%Pattern matching adds significant waste
Herringbone/chevron parquet15%Complex cuts at every border
L-Shaped and Irregular Rooms
Method 1: Divide into rectangles and add:
Section A: 4m x 3m = 12 m2
Section B: 2m x 2m = 4 m2
Total: 16 m2 + 10% = 17.6 m2
Method 2: Measure the bounding rectangle, subtract cut-outs:
6m x 3m = 18 m2 minus missing corner 2m x 1.5m = 3 m2
Net: 15 m2 + 10% = 16.5 m2
Note: Method 2 often works better for click-lock floors
because planks run the full length regardless of room shape.
Carpeting Stairs
Each stair step needs:
Tread (horizontal surface): typically 250mm (25cm) deep
Riser (vertical face): typically 190mm (19cm) high
Width: measure actual stair width
Per step: (25 + 19) cm = 44 cm of carpet length
For 12 stairs: 12 x 44 = 528 cm = 5.28m
Plus landing: measure separately
Plus 10-15% waste: 5.28 x 1.12 = 5.9m
At carpet width 4m, order: 5.9m x (stair width / 4m)
If stair is 0.9m wide and carpet is 4m wide:
You can cut ~4 stair widths from each 0.9m-wide carpet strip.
Efficient layout planning matters enormously for stairs.
Carpet from Roll: Width Planning
Carpet rolls come in standard widths: 3m, 4m, 5m
Room 5.5m x 4.5m:
Option A: 5m roll, run 5.5m lengthways
Need: 5.5m of a 5m roll — too narrow, needs seam
Option B: 4m roll, run 4.5m across 4m width — seam needed
Option C: 5m roll, run 4.5m lengthways across 5m width
Cut to 4.5m x 5.5m — need 4.5m length, no seam! ✓
Always sketch the roll direction before ordering.
Seams should run away from the main entrance and traffic flow.