Massetto
Calcola cemento, sabbia e acqua per massetto
🏗️Calculator
📐 Come Calcoliamo
The screed calculator uses the following formula:
Standard Mix: Typical screed uses 1:3 cement-to-sand ratio (by volume).
Shrinkage Factor: We use 1.15 to account for compaction and air voids during mixing.
About this floor screed calculator
This floor screed calculator estimates the cement, sand and water needed to lay a sand-and-cement screed over a floor. Enter the floor area and the screed thickness in millimetres, and the tool works out the wet volume, applies a 1.15 shrinkage factor and splits the dry volume into a standard 1:3 cement-to-sand mix before converting to kilograms.
Use it for levelling screeds over concrete slabs and underfloor heating. Typical screed thickness is 50–80 mm; thinner bonded screeds and thicker floating screeds are also supported.
🧮 Esempio di Calcolo
For a 20 m² floor with a 50 mm screed and a 1:3 mix:
- Wet volume = 20 × 0.05 = 1.0 m³
- Dry volume = 1.0 × 1.15 = 1.15 m³
- Cement = ¼ × 1.15 × 1400 kg/m³ ≈ 403 kg (9 × 50 kg bags)
- Sand = ¾ × 1.15 × 1600 kg/m³ ≈ 1,380 kg
- Water = 403 × 0.5 ≈ 200 L
Mix water in gradually — the 0.5 water-to-cement ratio is a guide, not a fixed amount.
💡 Practical tips
- Keep the screed at least 50 mm thick over insulation and 65 mm over underfloor heating pipes.
- A drier, crumbly mix that holds together when squeezed gives a stronger floor than a wet, sloppy one.
- Protect a fresh screed from fast drying for the first few days to avoid cracking.
- Allow roughly one day of drying per millimetre of thickness before laying floor finishes.
❓ Domande Frequenti
A standard sand-and-cement screed uses a 1:3 cement-to-sharp-sand ratio by volume, which is what this calculator assumes.
Most floor screeds are 50–80 mm thick. Bonded screeds can be thinner (25–40 mm) and screeds over underfloor heating are usually at least 65 mm.
For a 50 mm 1:3 screed you need roughly 20 kg of cement per m². The exact figure depends on thickness, which the calculator handles for you.
As a rule of thumb allow about one day per millimetre of thickness before laying tiles or wood. A 50 mm screed therefore needs roughly 50 days to fully dry.