Waterproofing calculator

Estimate outputs: Area, Material mass, Whole packages. Adjust Length, Width, Product consumption to match your project.

Inputs and units

Use the units shown beside each field. Replace the sample values with your measurements and the figures on the selected product packaging.

Parameter	Example input
Length	4 m
Width	3 m
Product consumption	1.5 kg/m²
Coats	2
Bag weight	10 kg
Waste allowance	10 %

Formula and assumptions

Material mass
Length × Width × Product consumption × Coats × (1 + Waste allowance / 100)

Whole packages
ceil(Material mass / Bag weight)

ceil = round up; floor = round down; max = the greater value. Trigonometric angles are converted from degrees to radians.

Allowance is applied before rounding to whole packages. Whole units are rounded up; displayed decimals are rounded only for readability.

Coverage depends on the product, substrate and installation method. Enter the supplier’s consumption figures; an area estimate cannot replace a cutting layout.

Waterproofing consumption is entered per coat in this tool. The bathroom project tool instead uses total consumption for the complete system.

Worked example

Sample values are examples, not product specifications. Run the calculation again with your own measurements.

Result	Calculation
Area	12 m²
Material mass	39.6 kg
Whole packages	4

Related calculators

Related tools use separate measurements. Check their inputs before transferring quantities.