Render quantity Calculator: measuring notes and method
Measure each coat separately
Record the net rendered area and applied thickness. Different base and finish products should be separate items with their own yields; a single combined thickness with one density can misrepresent the bags needed.
Translate a published consumption rate
A product rate expressed as kg/m² per mm can be multiplied by 1,000 to obtain kg/m³ for this model. Use the rate for the applied material, not loose powder bulk density.
Formula
Mass = area × applied thickness × density × (1 + waste ÷ 100). Bags = mass ÷ bag size, rounded up.
Worked examples in metric and imperial units
Illustrative values match Reset example and stay fixed when you edit the calculator. Both columns describe the same calculation; converted inputs are rounded.
Metric worked example
- Total surface area
- 24 m²
- Applied thickness
- 10 mm
- Material density
- 1,600 kg/m³
- Bag size
- 20 kg
- Waste allowance
- 10 %
Bags to buy: 22
Imperial worked example
- Total surface area
- 258.3339 ft²
- Applied thickness
- 0.3937 in
- Material density
- 99.8847 lb/ft³
- Bag size
- 44.0925 lb
- Waste allowance
- 10 %
Bags to buy: 22
Follow the calculation
Lengths in this working are in metres.
- Applied volume including allowance = 24 × 0.01 × 1.1 = 0.264 m³.
- Material mass = 0.264 × 1,600 = 422.4 kg.
- Divide by 20 kg per bag and round up.
Reviewed 19 October 2026. How calculations are checked · Report a correction