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Paint Calculator

Estimate paint required for walls, ceilings, or other surfaces using the net paintable area, product coverage rate, number of coats, and container size.

Calculate Paint and Cans

Subtract large doors, windows, and surfaces that will not be painted.

Litres = Area × Coats ÷ Coverage × (1 + Waste %); Cans = Ceiling(Litres ÷ Can size)

Painting 50 m² with two coats at 10 m²/L needs 10 L before waste. With 10% allowance, plan for 11 L, which is one 20 L can or an equivalent combination of smaller cans.

Measure the project carefully, use the effective product dimensions or coverage supplied by the manufacturer, add a realistic allowance, and round purchasing quantities up to saleable units.

Use this estimate before requesting quotations, comparing suppliers, preparing a budget, or checking whether delivered quantities match the planned project.

Do not mix units, use nominal dimensions where effective coverage is required, or treat a planning estimate as a structural specification.

Worked Example

Painting 50 m² with two coats at 10 m²/L needs 10 L before waste. With 10% allowance, plan for 11 L, which is one 20 L can or an equivalent combination of smaller cans.

Buying tip: Round up to the supplier’s available pack, bag, sheet, can, truck, or batch size after confirming the product specification.

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When to Use It

  • Room and house painting
  • Comparing product coverage
  • Planning primer and top coats
  • Estimating container sizes
  • Preparing supplier quotations

How It Works

  • Measure the real project dimensions.
  • Enter effective product coverage and waste.
  • Review and round the result to purchasable quantities.

Common Mistakes

  • Using wall floor area instead of paintable surface area
  • Ignoring the second coat
  • Assuming every paint has the same coverage
  • Forgetting porous or rough surfaces use more paint

Materials and Tools to Compare

  • Interior or exterior paint
  • Primer or sealer
  • Rollers, brushes, and trays
  • Masking tape and protective sheets

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Frequently Asked Questions

How do I calculate paintable area?

Add the area of the walls or ceilings and subtract large doors, windows, cupboards, or other surfaces that will not be painted.

Is the coverage rate exact?

No. Use the manufacturer\u2019s stated coverage as a guide. Rough, porous, repaired, or dark surfaces may use more paint.

Should primer be calculated separately?

Yes. Primer and top coat can have different coverage rates and may require different numbers of coats.

Why does the calculator round cans up?

Paint is sold in fixed container sizes, so the result rounds up to ensure enough product is available.

Can leftover paint be useful?

Yes. Properly stored leftover paint is useful for touch-ups, but avoid buying excessive quantities that may expire or change colour over time.

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