Calculate your result
Quick answer
For a hypothetical 40 m² surface, two coats at 10 m² per litre per coat need 8 L. A chosen 10% extra allowance makes 8.8 L, so two 5 L tins supply 10 L. Primer uses its own area, coats, coverage and tins. These are arithmetic examples, not product specifications.
How it works
Use the Paint Calculator South Africa to estimate finish paint and optional primer separately. Measure room walls, rectangles, known surface area or cylindrical pipe sides, then enter each product’s coverage per coat, coats, allowance and chosen tin size.
Formula
Required litres for each product = its net area in m² × its coats ÷ its coverage in m²/L per coat × (1 + its extra allowance/100). Full tins = round up(required litres ÷ chosen tin size).
Assumptions and common mistakes
Check units, input values and the method before relying on an estimate. Review the existing tool notes and official sources below.
Formula
Required litres for each product = its net area in m² × its coats ÷ its coverage in m²/L per coat × (1 + its extra allowance/100). Full tins = round up(required litres ÷ chosen tin size).
| Step | Calculation basis |
|---|---|
| Room walls | Room count × (2 × (length + width) × height − per-room openings) |
| Rectangles | (Combined one-face area − total openings) × matching faces |
| Pipe sides | π × outside diameter in metres × length × pipe count |
| Finish or primer litres | Its treated m² × its coats ÷ its m²/L per coat × its allowance |
| Purchase | Round each product to whole tins of its chosen size |
How much paint do I need?
Choose a measurement method and check the units. Room mode calculates wall area from perimeter × height, subtracts openings per identical room and repeats the result for the room count. Include the ceiling only when it will use the same finish product and colour. For a separate ceiling paint, use another calculation. Known net area must already include all required surfaces, faces and deductions.
Paint calculator m² and square feet
Select metres/m² or feet/square feet for surface measurements and deductions. Coverage always remains m² per litre per coat, and tin sizes remain litres. One square foot is 0.09290304 m². In rectangle mode, openings are the total across one face of all identical rectangles before multiplying matching faces. Measure reveals, returns, trims and different colours separately.
Coverage, coats and extra allowance
Use the exact product data for the substrate, finish, application method and required film build. A label rate per coat is different from coverage for the whole completed system. Roughness, porosity, colour change and application losses can alter practical consumption. Enter one extra allowance only when it is not already included in your confirmed practical rate. The example 10 m²/L, two coats and 10% are editable, not universal recommendations.
Dulux, Plascon and Jotun paint calculators
99tools is independent of these brands. Enter the current local data for the exact paint rather than a brand-wide coverage number. Product ranges from the same maker can have different spread rates and preparation requirements. A Boysen, Sherwin-Williams or Home Depot product, or a Dulux Nigeria formula, should not be assumed identical to a South African item with a similar name.
Drywall primer and finish paint
Choose whether a separate primer is specified. It can cover the entire net finish area or a smaller known patch area, with its own coat count, coverage, allowance, tin size and quote. Primer and finish litres are not interchangeable and are not combined into one purchase. The calculator does not decide whether a sealer, primer or undercoat is suitable or required for plaster, drywall, timber, masonry or metal.
Roof paint and exterior house surfaces
Use the actual specified coating area, not only house floor area or a roof footprint. For profiled roofing, confirm whether the coating take-off needs a developed-profile allowance beyond sloping projected area. Use the selected roof paint’s practical coverage and compatible preparation system. Painting does not automatically repair leaks or damaged substrates. Suspected asbestos needs specialist assessment before disturbance or cleaning.
Fences, pipes and structural steel
Flat fence rectangles count one or two matching faces, not the unseen area of posts, edges or widely spaced rails. Pipe mode uses outside cylindrical sides, π × outside diameter × length × count, excluding ends, interiors, flanges and fittings. Structural steel needs the actual developed surface area from the take-off and a specified coating system. This tool does not choose dry film thickness, volume solids, corrosion protection or a universal spray-loss factor.
Paint job estimates and time
Optional prices apply to full purchased tins. Labour uses net finish area for the agreed coat scope, with delivery and other quoted totals added once. Use one VAT basis; no extra VAT is added. Zero-price lines remain unpriced. Job duration also depends on preparation, crew, access, application, drying and permitted recoating conditions. Litres alone cannot establish completion time or a guaranteed quote.
Buying tins and exporting the result
The tool rounds each product to whole tins of one chosen size. It does not optimise a mixture of tin sizes or combine different colours and products. Check available sizes, tinting, batch consistency and returns with the supplier. Copy, print or download a CSV for Excel after calculating. The CSV is a result snapshot with coverage, coats, allowance and quantities, not a workbook with live formulas.
Reviewed by the 99tools team. Editorial and corrections policy.
Related painting and preparation tools
Paint planning guides
Frequently asked questions
How much paint do I need for a room?
Measure wall perimeter × height, subtract openings, then multiply by coats and divide by the selected product’s m²/L per coat. Add one chosen allowance and round to full tins. Calculate a different ceiling paint separately.
How much paint covers one square metre?
Litres per m² equal coats divided by coverage per coat, before any extra allowance. The rate depends on the exact product, substrate and required application.
Can I calculate ceiling paint separately?
Yes. Choose a rectangular surface or enter known ceiling area and use the ceiling product’s own coverage and coats.
Is this the Dulux or Plascon paint calculator?
No. 99tools is independent. Use the exact product data and compare area, coverage per coat, coats, allowances and tin rounding.
Does primer use the same coverage as finish paint?
Not necessarily. Enter separate primer data and its treated area. The tool rounds the primer purchase separately.
Can I use it for roof paint, pipes or fences?
Yes, with the correct measured or developed area and product data. Pipe mode counts only outside cylindrical sides, and flat fence mode excludes unmeasured edges, posts and fittings.
Does it calculate how long painting takes?
No. Quantity alone does not establish preparation time, crew productivity, drying or recoating. Use the installer’s scope and product conditions.
Can I download the result for Excel?
Yes. Download CSV for Excel saves a result snapshot, not an XLSX workbook with recalculating formulas.
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Helpful guides
How Much Paint Do I Need for Walls and Ceilings?
Measure the surfaces, use coverage per coat and round each paint product to tins without combining different finishes or colours.
Paint Coverage: Dulux, Plascon and Primer Data
Compare exact product coverage and coat requirements rather than using one spreading rate for an entire paint brand.
Paint Area for Roofs, Fences, Pipes and Steel
Use the actual treated surface and coating specification before calculating litres for exterior and shaped surfaces.