How Much Floor Levelling Compound Do I Need?
Quick Answer
Approximately 90–120 kg (~4 bags) for a 20m² room
Based on: 20m² floor area, 3mm average depth, 1.5–2 kg/m² per mm coverage rate
How We Calculated This
Floor levelling compound coverage is measured in kg per m² per mm of thickness. Most UK brands quote 1.5–2 kg/m²/mm:
- Area: 20m²
- Depth: 3mm
- Coverage rate: 1.5–2 kg/m²/mm
- Low estimate: 20 × 3 × 1.5 = 90 kg
- High estimate: 20 × 3 × 2.0 = 120 kg
- Bags (25 kg): 90–120 ÷ 25 = 4–5 bags
Common Coverage Rates by Product
- Mapei Ultraplan Renovation: ~1.5 kg/m²/mm
- Ardex K301: ~1.8 kg/m²/mm
- Setcrete High Performance: ~1.6 kg/m²/mm
- Weber Floor Flex: ~1.7 kg/m²/mm
Choosing the Right Depth
Measure the floor at multiple points to find the deepest dip. The depth you need is the difference between the highest and lowest points. For most domestic renovations, 2–5mm is typical. If the floor is badly uneven (over 10mm), consider a thicker fibre-reinforced compound or a sand/cement screed instead.
Preparation Tips
- Prime the substrate with SBR or acrylic primer — always follow the compound manufacturer’s instructions
- Fill any deep holes or cracks with a repair mortar first
- Ensure the room temperature is above 5°C
- Work quickly — most compounds have a 15–20 minute working time
Last updated: April 2026