Paint Calculator
Calculate paint needed for walls, ceilings, and trim
How to Calculate Paint for Your Room
Calculating the right amount of paint for your room is essential to avoid waste and ensure you have enough to complete your project. Our free paint calculator takes the guesswork out of estimating paint quantities.
What You Need to Know
- Room dimensions: Measure the length, width, and height of your room in feet or meters.
- Surface types: Walls, ceilings, trim, and doors have different coverage rates.
- Number of coats: Most paint jobs require 2 coats for even coverage.
- Deductions: Subtract door and window areas for accurate estimates.
Paint Coverage Rates
Standard interior paint typically covers approximately 350-400 square feet per gallon (about 32-37 square meters per liter). Coverage varies based on:
- Surface texture (smooth vs textured walls)
- Paint quality and type
- Color change (light to dark requires more paint)
- Application method (brush, roller, or sprayer)
Frequently Asked Questions
How many square feet does a gallon of paint cover?
A gallon of interior paint typically covers 350-400 square feet per coat. Coverage varies based on surface texture, paint quality, and application method. Our calculator uses industry-standard coverage rates and adjusts for your specific project needs.
Should I include primer in my calculation?
Primer is recommended when painting new drywall, covering dark colors, or painting over stains. Primer typically covers about 200-300 square feet per gallon. Our calculator can include primer estimates when you enable this option.
How do I account for doors and windows?
Standard doors are approximately 21 square feet and windows are about 12 square feet. Our calculator deducts these areas automatically when you specify the number of doors and windows in your room.
What waste factor should I use?
We recommend a 10% waste factor for most projects. This accounts for touch-ups, drips, and coverage variations. For textured surfaces or inexperienced painters, consider using 15% waste.
How do I calculate paint for trim and doors?
Trim typically requires about 10% of the wall paint volume. Doors require approximately 0.5 quarts per door for 2 coats. Our calculator provides separate estimates for each surface type.