Calculator
Engineering
MathPaint Calculator
Free online paint calculator to estimate the amount of paint needed for walls, rooms, and surfaces. Calculate paint quantity in liters and gallons based on room dimensions, coats, and coverage rate. Perfect for home painting projects.
What is a Paint Calculator?
A Paint Calculator is a practical tool for estimating the amount of paint needed for your painting project. By entering room dimensions, number of coats, and paint coverage rate, the calculator determines the total paintable area and paint quantity required. It accounts for doors and windows to give you a more accurate estimate, helping you avoid buying too much or too little paint.
How to Use the Paint Calculator
- Enter the room length, width, and wall height in your preferred unit (meters or feet)
- Specify the number of paint coats you plan to apply (typically 1-3 coats)
- Enter the paint coverage rate (usually found on the paint can label, typically 10-12 m²/L or 350-400 ft²/gallon)
- Optionally, enter the number of doors and windows to subtract their area from the total
- Click Calculate to see the total paint needed and number of cans required
- Use the cost estimate section to calculate the total project cost
Paint Calculation Formulas
1. Wall Area = 2 × (Length + Width) × Height
2. Paintable Area = Wall Area - (Doors Area + Windows Area)
3. Paint Needed = (Paintable Area × Number of Coats) / Coverage Rate
Tips for Accurate Paint Estimation
- Always add 5-10% extra paint to account for touch-ups and uneven surfaces
- Different surfaces require different coverage rates - rough or porous surfaces need more paint
- Darker colors may require additional coats for full coverage
- Primer typically has different coverage rates than finish paint
- One gallon covers approximately 350-400 square feet (32-37 m²) on smooth surfaces
- Store leftover paint properly for future touch-ups
- Check the paint can label for manufacturer's recommended coverage rate
Understanding Paint Coverage
Paint coverage refers to the area that can be painted with a specific volume of paint. Coverage rates vary based on surface texture, paint quality, application method, and color. Smooth, sealed surfaces require less paint, while rough, porous, or textured surfaces absorb more paint and reduce coverage. High-quality paints often provide better coverage than cheaper alternatives. The standard coverage for interior wall paint is approximately 10-12 m²/liter (350-400 ft²/gallon) on smooth surfaces.
Common Paint Estimation Mistakes
- Not accounting for surface texture and porosity
- Forgetting to subtract door and window areas
- Underestimating the number of coats needed for dark colors
- Not adding extra paint for waste and touch-ups
- Using incorrect coverage rates for different paint types
- Not considering ceiling paint if needed