Stucco Calculator
Calculate the number of bags of stucco, render or plaster needed for any wall area, adjustable for coat thickness and number of coats.
What this calculates
Calculates the total wall area, area with waste allowance, total material needed in kg and the number of bags required for stucco, render or plaster.
Formula used
Area = length × height. Area with waste = area × (1 + waste %). Total kg = area with waste × coverage × coats. Bags = total kg ÷ bag size (rounded up).
Worked example
A wall of 6 m × 2.5 m = 15 m². With 10% waste: 16.5 m². Two coats at 16 m²/bag: 16.5 × 16 × 2 ÷ 25 = ... = 22 bags of 25 kg.
Typical coverage by product
Basecoat render (site-mixed): 12–14 m²/25 kg at 10 mm. Pre-mixed polymer render: 14–20 m²/25 kg. Finish coat (3–5 mm): 20–30 m²/25 kg. Always check the product datasheet for the manufacturer's stated yield.
When not to use this calculator
Spray-applied stucco, EIFS (exterior insulation and finish systems) and specialist decorative finishes have very different coverage rates. Use manufacturer data for those products.
Frequently asked questions
How many bags of stucco per m²?
Typically 12–20 m² per 25 kg bag depending on coat thickness. Enter the manufacturer's coverage figure for the most accurate result.
How many coats of stucco do I need?
2 coats for most applications: a basecoat and a finish coat. Traditional 3-coat systems add a scratch coat before the brown coat.
What is the difference between stucco and render?
They are the same material — "stucco" is the North American term and "render" is used in the UK and Australia. Both are cement or lime-based wall coatings.
Can I apply stucco over drywall?
Not for exterior use without a water-resistant barrier and metal lath. Interior skim coats can be applied directly to drywall.
Assumptions
- Coverage entered is per coat per bag.
- Waste is applied to the surface area before multiplying by coats.
- Does not include metal lath, waterproof membrane, primers or corner beads.
Coverage rates vary significantly by product formulation, application thickness and substrate absorption. Always verify against the product datasheet before ordering materials.
Common mistakes
- Applying stucco too thick in one coat — maximum 15 mm per coat for most products.
- Not misting the previous coat before applying the next one.
- Working in direct sunlight or high temperatures without shading.