Cement Render Calculator
Estimate cement-render area, wet volume, full bags, coat coverage, material weight and cost after opening deductions.
Default project preview
19 bags
Net wall area
200 ft²
Wet render volume
9.17 ft³
Total coat area
400 ft²-coats
Total thickness
0.5 in
Calculator
Build the material order
Your order will appear here
Enter the project details and calculate a rounded material estimate.
Input and output guide
What each value means
The labels and units below are part of this calculator’s visible methodology. Replace every default with measurements or product data from the actual project.
Wall length
Enter this project assumption in ft. The current imperial default is 30 ft.
Wall height
Enter this project assumption in ft. The current imperial default is 8 ft.
Door and window area
Enter this project assumption in ft². The current imperial default is 40 ft². Minimum: 0.
Render coats
Enter this project assumption in a unitless value. The current imperial default is 2. Minimum: 1.
Thickness per coat
Enter this project assumption in in. The current imperial default is 0.25 in.
Waste allowance
Enter this project assumption in %. The current imperial default is 10 %. Minimum: 0. Maximum: 50.
Wet yield per bag
Enter this project assumption in ft³. The current imperial default is 0.5 ft³.
Dry weight per bag
Enter this project assumption in lb. The current imperial default is 55 lb.
Price per bag
Enter this project assumption in a unitless value. The current imperial default is 12. Minimum: 0.
How to read the outputs
Net wall area
openings deducted. Default preview: 200 ft².
Wet render volume
allowance included. Default preview: 9.17 ft³.
Total coat area
area × coats. Default preview: 400 ft²-coats.
Total thickness
entered coat thicknesses. Default preview: 0.5 in.
Dry bag weight
full bags. Default preview: 1,045 lb.
Material cost
render bags only. Default preview: $228.00.
Methodology
Transparent calculation
BuildMeter converts every input to a consistent internal unit, applies the selected allowance, and rounds products up to whole purchasable units.
Net area = wall area − openings. Wet volume = net area × thickness per coat × coats × waste factor. Bags = round up (wet volume ÷ bag yield).
Reviewed project guidance
How to use this estimate in a real project
Last reviewed: July 30, 2026
Estimate render volume, dry-material quantity and package count from wall area, thickness and product yield.
Calculation steps
- 1Enter the actual project dimensions or operating values.
- 2Apply the calculator formula using consistent units.
- 3Review the unrounded result and the editable allowance.
- 4Round only to the product, stock length or equipment increment actually purchased.
Worked numerical example
A 100 m² wall rendered 12 mm thick requires 1.2 m³ of placed render before waste and substrate variation.
Purchasing and rounding
Use the render manufacturer's stated yield at the specified coat thickness when converting wall area to bags. Substrate irregularity can consume substantially more material than a flat-wall calculation, so keep leveling or dubbing-out material separate from the finish-coat allowance.
Interpret the result
The calculated volume is the theoretical placed render for the entered area and thickness. Bag count depends on product yield and substrate condition; a large difference between theoretical volume and purchased mass should be checked against density, coat build and the manufacturer's coverage data.
Page-specific assumptions
- Inputs describe one consistent project condition.
- Entered yields and efficiencies match the selected product or equipment.
- Site-specific code and engineering requirements are checked separately.
Common mistakes
- Mixing imperial and metric inputs.
- Using nominal dimensions where actual coverage controls.
- Rounding intermediate values too early.
- Treating a quantity estimate as design approval.
Primary and technical references
BuildMeter provides planning estimates, not engineering, architectural, electrical, mechanical, plumbing, permit or code approval. Review the methodology and verify final decisions with product documentation and qualified professionals.
BuildMeter Guides
Understand the measurements and assumptions
Use these visible reference guides before changing project inputs or planning allowances.
FAQ
Cement Render Calculator questions
Should openings be deducted?+
Large doors and windows can be deducted, while reveals and small returns may partly offset that reduction.
Why enter wet yield instead of bag coverage?+
Render thickness directly controls volume, so wet yield allows the calculation to respond to both area and coat thickness.
Does this choose a render mix?+
No. Use a compatible system for the substrate, exposure and finish specification.