Paint Calculator
Paint = (Wall area × Coats) / Coverage
ConstructionHow to Use This Tool
How the Paint Calculator Works
Enter your room’s length, width, and wall height, plus the number of coats and the paint’s coverage (typically 10 m²/L or 350 ft²/gal). The calculator estimates total paint needed.
The Formula
Paint needed (liters) = (Wall area × Number of coats) / Coverage per liter
Wall area = perimeter × height = 2 × (length + width) × height
Tips for Accurate Estimation
- Coverage varies by paint: Most interior paints cover 10-12 m²/L per coat. Check your paint can for the exact figure.
- Subtract doors and windows: For a more accurate estimate, subtract about 1.5 m² per door and 1 m² per window from the wall area.
- Buy 10% extra: Always buy a bit more than calculated to allow for touch-ups and color matching.
- Primer is separate: If you’re painting bare drywall or making a drastic color change, factor in primer separately.
Formula & Explanation
The calculator computes wall area as perimeter × height. It does not subtract doors and windows automatically — subtract approximately 1.5 m² per standard door and 1 m² per standard window for a more accurate estimate.
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Frequently Asked Questions
How much paint do I need for a 4u00d73 meter room?
A 4u00d73 m room with 2.4 m ceiling height has a wall area of 2 u00d7 (4+3) u00d7 2.4 = 33.6 mu00b2. With 2 coats and 10 mu00b2/L coverage, you'd need about 6.7 liters of paint.
How many coats of paint do I need?
Two coats is standard for most interior walls. You may need a third coat when painting over a dark color with a light one, or with lower-quality paint. Primer may be needed as a separate base coat.
Does this calculator include the ceiling?
No, this calculator covers walls only. To include the ceiling, add length u00d7 width to the wall area before applying the coats/coverage calculation.