Room surface area calculator

Estimate outputs: Floor area with allowance, Net wall area, Linear length. Adjust Length, Width, Height 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	5 m
Width	4 m
Height	2.7 m
Openings area	4 m²

Formula and assumptions

Floor area with allowance
Length × Width

Net wall area
max(0, 2 × (Length + Width) × Height - Openings area)

Linear length
2 × (Length + Width)

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.

Worked example

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

Result	Calculation
Floor area with allowance	20 m²
Net wall area	44.6 m²
Linear length	18 m

Related calculators

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