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Paint and Wall Area Calculator

Use this paint and wall area calculator entirely in your browser.

ResultPaint required: 7.84 L

Gross wall area: 43.20 m²

Paintable area after openings: 39.20 m²

Coverage calculation: 39.20 m² × 2 coats ÷ 10 m²/L

Surface condition, application method, paint opacity, and manufacturer coverage can change the quantity required.

Calculations happen locally in your browser.

How to use this calculator

  1. Enter the labelled values and review the live result.
  2. Review the live result and use Copy result when you need to share it.

How the calculation works

The perimeter is multiplied by wall height, openings are subtracted, and paintable area is multiplied by coats and divided by the coverage entered.

Formula

Litres = ((2 × (length + width) × height − openings) × coats) ÷ stated coverage

Step-by-step calculation

  1. Enter the labelled values and review the live result.
  2. The perimeter is multiplied by wall height, openings are subtracted, and paintable area is multiplied by coats and divided by the coverage entered.
  3. Check the displayed result, then copy it if needed.

Worked example

A 5 m by 4 m room, 2.4 m high, with 4 m² of openings and two coats at 10 m²/L requires about 7.84 L.

Risk guidance

From room size to paintable area

The calculator models four rectangular walls, subtracts the opening area you enter, and applies the number of coats. Ceilings, trim, alcoves, and irregular surfaces need separate measurements.

Use the product's stated coverage

Coverage varies with paint, surface porosity, colour change, tools, and application. Enter the manufacturer's coverage figure and confirm container sizes before buying.

Frequently asked questions

Does this tool send my inputs anywhere?

No. The interactive calculation runs in your browser and this site does not submit tool inputs to a backend.

How should I use the result?

Use it for early planning only. Verify measurements, definitions, current local requirements, and the complete design with the relevant authority and appropriately qualified professionals.

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