Paint calculator
Calculate paint from area, coats and the manufacturer coverage rate.
20 LAUNCH TOOLS
Choose a calculator
When to use it
Use after measuring paintable wall or ceiling area and checking product coverage.
How it works
Litres = area × coats ÷ coverage rate.
Worked example
Assume 40 m² of measured paintable area, two finish coats and the chosen paint’s stated coverage of 12 m²/L. 40 × 2 ÷ 12 = 6.666…, so the planning quantity is 6.67 litres before choosing available tin sizes. This example does not include a separate primer or an extra allowance.
Measurement guidance
Paintable area, number of coats and manufacturer coverage in m²/L.
Buying and specification checks
Coverage comes from the chosen product; porous or repaired surfaces can use more.
Prepare the surfaces and the plan
The litre result is useful only when the measured surface and coating assumptions are sound.
- List walls, ceilings and trim separately when they use different products, colours or coat counts.
- Investigate recurring damp, unstable plaster and uncertain old coatings before creating dust or covering the symptom.
- Use the chosen coating system’s instructions for cleaning, repairs, primer or first coat, application and recoat conditions.
- Plan floor and furniture protection, suitable access, ventilation and room use around preparation and drying.
Common mistakes
- Using floor area for walls
- Forgetting extra coats
- Using optimistic coverage on porous surfaces
FREE TOOL AND PROJECT PACK
What the free calculator provides
The free calculator converts a measured paintable area, coat count and the selected paint’s stated coverage into a transparent litre estimate. It does not choose the coating system, diagnose the surface or select tin sizes.
What the dedicated pack adds
The dedicated pack turns that quantity into a recorded ordinary interior decorating plan.
- Room scope, surface assessment, colour testing and compatible coating-system checks.
- Preparation, primer, finish, quantity, tools, protection, budget and drying records.
- Application checkpoints, troubleshooting, completion, care and a retained finish passport.
20-page printable digital workbook (PDF). Immediate digital delivery with 90-day access; no subscription.
Practical FAQs
Why is my litre total higher than the wall area suggests?
Paint is calculated by coat coverage, not wall area alone. Multiply the paintable area by the number of coats, then divide by the exact product’s stated coverage.
Should primer be included in the same litre total?
No. Estimate primer or an initial coat separately using that product’s own coverage and instructions. Do not treat every first coat as the same product or dilution.
How do I turn litres into tins to buy?
Compare the calculated litres with the sizes sold for the selected product and colour. Round to a workable combination without assuming leftover paint or another colour can cover the shortfall.
Can I paint over damp, flaking or uncertain old paint?
Do not use a new coat to hide an unresolved cause. Establish a compatible preparation method first, and obtain suitable assessment before disturbing a coating that may contain lead or another hazardous material.
Planning guidance, not a quotation or a substitute for project-specific design and competent advice.