Paint Coverage Calculator

This paint calculator helps you determine how much paint and primer you need for your room painting project. It calculates wall and ceiling areas, subtracts openings like doors and windows, and provides accurate paint volume estimates.

1. Measure your room: Use a tape measure to find the length, width, and height of your room in millimeters. For best results, measure along the floor and in corners where walls meet.
2. Count openings: Count the number of doors and windows. We use standard sizes (1.9 m² for doors, 1.5 m² for windows) to calculate area deductions.
3. Select surfaces and coats: Choose whether you're painting walls only, ceiling only, or both. Specify the number of coats (2 is typical for most projects).
4. Adjust coverage rate: Most interior paints cover 10-12 m² per liter. Check your paint can for specific coverage information. Textured or porous surfaces may require more paint.
5. Add primer if needed: Enable primer calculation if you're painting new drywall, covering stains, or making dramatic color changes. Primer has lower coverage (typically 8 m²/L).
6. Review your results: The calculator shows total paint needed, primer volume (if selected), net paintable area, and a detailed breakdown of all surfaces. A 10% waste factor is included by default.

Formula: Paint needed (L) = (Net Area × Coats) ÷ Coverage Rate × (1 + Waste %)

Pro tip: Buy paint in slightly larger quantities than calculated. It's difficult to match custom colors later, and having extra paint for touch-ups is invaluable. Store leftover paint in a cool, dry place with the lid tightly sealed.