Calcufast

Paint calculator: liters and cans

Estimate paint to buy for walls or ceilings. Subtract doors and windows, use your product's coverage and calculate whole cans, leftover paint and cost.

Enter measurements in meters. Repeat identical surfaces or add different ones. All surfaces must use the same paint and coverage.

Surface 1

Check the technical sheet: if coverage already includes every coat in the finish, do not multiply it by coats again.

Add the m² of doors, windows or other excluded areas. Leave 0 if none.

From 1 to 10. Follow the manufacturer's surface preparation and coat instructions.

m² covered by 1 liter, on the basis selected above. Convert coverage per can to m²/L first.

From 0% to 100%, added to the calculated liters. Not a substitute for coverage suited to the surface.

Liters per can. For example, 4 or 19 if the label says so; do not assume all gallons have the same volume.

Leave blank to calculate quantities only. Excludes labor and other materials.

Your can count and estimated leftover paint will appear here.

From surfaces to cans

Measure each rectangular surface in meters. Use the quantity for identical walls; add another surface for different dimensions or a ceiling. Subtract doors, windows and areas you will not paint. Do not count a wall twice.

Coverage must suit the actual product and surface. There is no universal figure: texture, absorption, previous color, preparation and application method affect consumption. Check the technical sheet and test the surface when appropriate.

Per coat is not the same as complete finish

If the label states m²/L per coat, the calculator multiplies by your chosen number of coats. If it states m²/L for the complete finish, that coverage already includes the system's coats and is not multiplied again.

If coverage is listed per can, divide by the can's liters before entering it. An illustrative 40 m² per 4 L can equals 10 m²/L, keeping the same basis: per coat or complete finish.

Liters and purchase

Net area = sum(width × height × quantity) − excluded area. Liters = net area / coverage × coat factor × (1 + waste / 100). Cans = round up(liters / can volume).

The coat factor is your number of coats for per-coat coverage; it is 1 for complete-finish coverage. Cost equals cans × price per can. Excludes primer, thinner, tools, labor and delivery.

Example: four identical walls

Four 5 × 2.5 m walls total 50 m². Subtract 6 m² of doors and windows to leave 44 m². With illustrative coverage of 10 m²/L per coat, 2 coats and 10% waste, you need 9.68 L.

| Purchase with 4 L cans | Result | |---|---:| | Whole cans | 3 | | Liters purchased | 12 L | | Estimated leftover | 2.32 L | | Cost if each can is priced at 25 | 75 |

These are illustrative inputs, not recommended coverage, waste or prices. With 10 m²/L complete-finish coverage, the same example needs 4.84 L and two cans, not three. Estimated leftover is the whole-can surplus after allowing for waste.

Frequently asked questions

Divide net area by coverage in m²/L. Multiply by coats only if coverage is stated per coat, then add your chosen waste allowance.

The tool calculates whole cans of one size. If you need 9.68 L and buy 4 L cans, that means three cans: 12 L purchased and an estimated 2.32 L left over.

Do not multiply by coats again. Use the manufacturer's complete-system coverage and select that option to avoid counting paint twice.

Limitations

One can size per simulation; this is not an optimizer for mixed sizes. Use the label's liters: US gallons, imperial gallons and commercial can sizes are not interchangeable. Break irregular surfaces into measurable parts.

As a reference on estimation limits, Sherwin-Williams notes that quantities depend on application method and surface condition. This calculator does not import its prices or coverage rates: enter those for your own product.