About this calculator

Traditional EU external render is a 6:1:1 sand:cement:lime mix at 12–20 mm. For 15 mm cover, you need ~0.018 m³ of mortar per m². 1 m³ of mortar uses ~1.6 t sand, 300 kg cement and 100 kg hydrated lime.

Frequently asked questions

What does the External Render Mix Calculator do?

Sand, cement and lime for a sand:cement:lime external render at 15 mm thickness. Traditional EU external render is a 6:1:1 sand:cement:lime mix at 12–20 mm. For 15 mm cover, you need ~0.018 m³ of mortar per m². 1 m³ of mortar uses ~1.6 t sand, 300 kg cement and 100 kg hydrated lime.

Is the External Render Mix Calculator free to use?

Yes. Every calculator on Calcurly.com is free, works in your browser without sign-up, and can be embedded on your own website.

How accurate is the External Render Mix Calculator?

Results are calculated in real time using industry-standard formulas. Treat the output as a well-informed estimate — always cross-check with local regulations, product datasheets, or a qualified rendering & stucco professional before committing to a purchase or a job.

What inputs does the External Render Mix Calculator need?

Enter values for: Wall area (m²), Thickness (mm). Sensible defaults are pre-filled where possible so you can start with a single change.

Can I embed the External Render Mix Calculator on my own website?

Yes — copy the iframe snippet at the bottom of this page, or use the Embed Generator to customise the size. The embedded version stays in sync with the live calculator on Calcurly.com.