Rendering calculator
Set the wall area, the number of coats and thickness, and the ratio for scratch and top coats. It returns cement bags and sand so the render is ordered once and mixed consistently.
Pricing the job? Open EstiMate free and these quantities go straight onto the materials list with your prices.
How it works out the quantities
- 1Render volume per coat = area × thickness. A typical two-coat system is a 10–12 mm scratch coat and a 6–8 mm top coat.
- 2Scratch coats are usually 1:4 or 1:5 with waterproofer; top coats slightly weaker (1:5 or 1:6) so they don't crack over the base.
- 3Cement is converted to 25 kg bags and sand to tonnes with the ratio you set for each coat.
- 4Waste of 10–15% allows for keying, uneven backgrounds and material lost off the hawk.
Site tips before you order
- Use a sharp or rendering sand, not soft building sand, for external render.
- Bell beads, stop beads and mesh over movement joints are separate lines on the quote.
- Monocouche (through-coloured) render is priced by bags per m² from the manufacturer — this calculator is for sand and cement.
- Scaffold or a tower is nearly always needed; price access as its own line.
Common questions
What's the mix for sand and cement render?
Scratch coat 1:4 to 1:5 cement:sand with waterproofer; top coat 1:5 to 1:6. Weaker on softer backgrounds to avoid cracking.
How thick should render be?
Around 16–20 mm in two coats: a 10–12 mm scratch coat and a 6–8 mm finish. Thicker single coats crack.
How much sand and cement to render 50 m² at 18 mm?
About 0.9 m³ of render — roughly 1.5 t of sand and 12–14 bags of cement across both coats at 1:5, plus waste. The calculator gives the exact split per coat.
Does it cover monocouche?
Not directly — monocouche uses proprietary bags at a stated coverage per m² per mm; use the manufacturer's figure on your quote.
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