Floor Levelling Calculator — Compound & Materials Estimator

Our floor levelling calculator estimates the amount of compound needed based on your floor area and the average depth of unevenness. Different products have different coverage rates and are designed for different depth ranges.

The formula

Bags needed = (Area × Average depth × Coverage rate) ÷ Bag size

For example, levelling 15 m² at an average 3mm depth with self-levelling compound (1.6 kg/m²/mm): 15 × 3 × 1.6 = 72 kg ÷ 25 = 3 bags (before wastage).

Coverage rates by product type

• Self-levelling compound: 1.6 kg/m²/mm — best for 2–5mm depth, flows to a level finish (e.g. Mapei Ultraplan; Weber and Setcrete High Performance run a little higher at ~1.7)
• Floor patch/repair: 1.5 kg/m²/mm — for localised dips and feathered repairs, 1–10mm (e.g. Mapei Planipatch; Planipatch Xtra 1.4)
• Deep fill compound: 1.9 kg/m²/mm — for 5–50mm depth, often used before self-levelling (e.g. Setcrete Deep Base ≈1.86 kg/m²/mm at 5mm rising to ~2.0 at 20–50mm)

These rates are based on typical UK products from Setcrete, Mapei, Weber and Ardex ranges. Deep-fill compounds are the heaviest per millimetre and patch/feather compounds the lightest, so always pick the product type that matches your depth and check the manufacturer's data sheet for the exact coverage rate. Primer is estimated at around 10 m² per litre (typical neat acrylic floor primer); diluting on porous screed can stretch this much further, so follow your primer's instructions.