# Paint Coverage Calculator

> Estimate the paint for a room from its size, doors, windows, number of coats and the coverage on the tin, in litres, US gallons and cans.

Category: Construction · Applies to: Worldwide · Last updated: 2026-10-29
Interactive calculator: https://calculators.geekmidst.com/calculators/paint-coverage-calculator

Paint needed is the area to paint times the number of coats, divided by the coverage printed on the tin (m² per litre or ft² per gallon).

Also called: Paint estimator, Wall paint calculator.

## Inputs
- Units (options: Metric, Imperial; default metric)
- Room length (default 4)
- Room width (default 3.5)
- Wall height (default 2.5)
- Doors (default 1; optional)
- Area of each door (default 1.9; optional)
- Windows (default 2; optional)
- Area of each window (default 1.5; optional)
- Paint the ceiling too (options: No, Yes; default no)
- Coats (default 2)
- Coverage per coat (default 10)
- Can size (default 4)

## Results
- Paint needed
- Paint needed
- Cans to buy
- Area to paint
- Area to paint

## Formula

```
Area = 2(L + W) × H − Doors − Windows (+ L × W for the ceiling);  Paint = Area × Coats ÷ Coverage
```

Where:
- L, W, H: room length, width and wall height
- Coverage: area one litre or gallon covers in one coat

## Worked example
1. Walls = 2 × (4 + 3.5) × 2.5 = 37.5 m²; less 1.9 m² door and 2 × 1.5 m² windows = 32.6 m².
2. Paint = 32.6 × 2 coats ÷ 10 m²/L = 6.52 L.
3. 6.52 ÷ 4 L = 1.63 → 2 cans.

**Result:** Two coats on a 4 × 3.5 m room with 2.5 m walls take about 6.5 litres, so two 4-litre cans.

## What the result means

Primer, a big colour change or fresh plaster usually needs an extra coat. Check the coverage on your actual product; it ranges widely.

## Assumptions and limits
- Coverage is the same for every coat.
- Trim, skirting and doors themselves are not painted.
- Textured or porous surfaces can halve the real coverage.

## Questions

### How much does a litre of paint cover?

Many emulsions state 10–14 m² per litre per coat on smooth walls; a US gallon typically covers 350–400 ft².

### Should I subtract doors and windows?

Yes for large openings. For a small room, leaving them in gives a useful margin.

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- [Drywall Sheet Count Calculator](https://calculators.geekmidst.com/calculators/drywall-sheet-count-calculator)
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_Quantities are estimates. Confirm requirements with your engineer or supplier before ordering materials._

Source: GM¹X CalcVerse — https://calculators.geekmidst.com/calculators/paint-coverage-calculator