Free plaster (Putz) calculator: how much interior plaster or exterior render you need per m² — total kg, number of bags and volume in m³ from the wall area and the layer thickness.
Reference for lime-cement plaster (~1.4 kg per m² and per mm of thickness):
| Thickness | Material | Volume |
|---|---|---|
| 8 mm | ~11 kg/m² | 0.008 m³/m² |
| 10 mm | ~14 kg/m² | 0.010 m³/m² |
| 15 mm | ~21 kg/m² | 0.015 m³/m² |
| 20 mm | ~28 kg/m² | 0.020 m³/m² |
| 25 mm | ~35 kg/m² | 0.025 m³/m² |
Material (kg) = area × thickness (mm) × consumption (kg/m²/mm). Volume (m³) = area × thickness ÷ 1000. Bags = material ÷ bag size (rounded up).
Working on the floor instead? Use our Screed Calculator (Estrich) – m³, kg & Bags.
Lime-cement plaster uses about 1.4 kg per m² and per mm of thickness. For a 15 mm layer that is ~21 kg/m². Gypsum plaster is lighter (~0.9 kg/m²/mm).
Interior plaster is usually 10-15 mm (gypsum from ~8 mm, lime-cement ~15 mm). Exterior render is typically 15-20 mm, applied in two coats.
Total kg = area × thickness (mm) × consumption (kg/m²/mm). Divide by the bag size (e.g. 30 kg) and round up. Add 5-10% for waste and an uneven wall.