Paint & Color

Paint Quantity Calculator

Estimate the litres of finish paint needed for a rectangular room after doors and windows are removed.

Free interactive tool

Enter your details

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m
m
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Method & guidance

How the Paint Quantity Calculator works

Net wall area is multiplied by the coat count and waste allowance, then divided by the selected paint coverage.

How to use this tool

  1. Collect accurate values for room length, room width, wall height.
  2. Enter measurements in the displayed units and select the choices that match this project.
  3. Select Calculate / Generate, then compare the outputs with the stated Paint Quantity Calculator method.
  4. Apply the result only after checking product specifications and real site conditions.

Example calculation or use case

For a worked Paint Quantity Calculator example, use Room length = 4 m, Room width = 3.5 m, Wall height = 2.7 m, Doors and windows = 4 m². The tool then applies this method: Net wall area is multiplied by the coat count and waste allowance, then divided by the selected paint coverage.

Frequently Asked Questions

What information does the Paint Quantity Calculator use?

It uses the measurements and choices shown in the form. Net wall area is multiplied by the coat count and waste allowance, then divided by the selected paint coverage.

How accurate is the Paint Quantity Calculator result?

The calculation is mathematically consistent with the stated assumptions. Textured walls and dramatic color changes often need the full waste allowance. Real products, site conditions, and supplier specifications can still change the final decision.

Should I include an allowance?

Yes. Use a waste allowance appropriate to the product, pattern, and installation complexity.

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