Paint Calculator
Calculate paint needed for walls, ceilings, and trim. Get accurate estimates including primer and multiple coats.
Room Dimensions
Openings
Paint Details
Paint Needed
2.5 gallons
Plus 1 gallon primer
How to Calculate Paint for Your Project
Buying the right amount of paint saves time and money. Too little means mid-project store runs and color matching issues. Too much means wasted paint. This calculator helps you determine exactly how much paint and primer you need.
Paint Coverage Formula
Standard paint coverage is 350-400 square feet per gallon for one coat. However, actual coverage varies based on:
- Surface texture: Smooth drywall vs. textured/popcorn
- Porosity: New drywall absorbs more paint than sealed surfaces
- Paint quality: Premium paints have better coverage
- Application method: Spraying uses more paint than rolling
- Color change: Light to dark uses less than dark to light
Wall Area Calculation
Calculate total wall area: (Length + Width) × 2 × Height
Subtract doors (20 sq ft each) and windows (15 sq ft each). For standard rooms with 1-2 doors and windows, you can skip subtracting—this accounts for waste and touch-ups.
How Many Coats Do You Need?
- 1 coat: Touch-ups, same color refresh
- 2 coats: Standard for most projects
- 3 coats: Dark to light colors, high-contrast changes
- Primer + 2 coats: New drywall, stain coverage, major color changes
When to Use Primer
Always use primer for:
- New or repaired drywall
- Dark to light color changes
- Covering stains (water, smoke, marker)
- Painting over glossy surfaces
- Switching from oil-based to latex paint
- Bare wood or metal
Paint Types and Coverage
Flat/Matte Paint
Best coverage, hides imperfections. Covers 400+ sq ft per gallon. Ideal for low-traffic areas and ceilings.
Eggshell/Satin
Covers 350-400 sq ft per gallon. Washable, good for living rooms and bedrooms.
Semi-Gloss
Covers 350-400 sq ft per gallon. Durable, moisture-resistant. Best for kitchens, bathrooms, trim.
High-Gloss
Covers 300-350 sq ft per gallon. Highly reflective, shows imperfections. Used for trim and doors.
Important Notes
Always buy paint from the same batch to avoid color variations. Keep records of paint brand, color name, and batch number for future touch-ups.
Paint has a shelf life of 2-10 years if stored properly. Seal cans tightly and store in climate-controlled areas.
Professional painting typically costs $2-6 per square foot including labor, supplies, and materials.
Frequently Asked Questions
How much area does a gallon of paint cover?
One gallon of paint typically covers 350-400 square feet with one coat on smooth surfaces. Textured walls, porous surfaces, or darker colors may reduce coverage to 300 square feet per gallon.
How many coats of paint do I need?
Most projects need 2 coats for even coverage and color depth. Dramatic color changes or covering dark colors may require 3 coats. Always use primer when changing from dark to light colors or painting new drywall.
Do I need to subtract doors and windows?
For standard rooms with 1-3 doors and windows, you can skip subtracting—this extra paint accounts for touch-ups and waste. For rooms with large windows or multiple doors, subtract approximately 20 sq ft per door and 15 sq ft per window.
How much does a gallon of paint cost?
Paint prices range from $25-$40 for budget brands to $50-$80+ for premium brands like Benjamin Moore, Sherwin-Williams, or Farrow & Ball. Higher quality paint often provides better coverage, requiring fewer coats.
Should I use primer?
Use primer for new drywall, dramatic color changes, covering stains or dark colors, or painting over glossy surfaces. Self-priming paints (paint + primer in one) work well for minor touch-ups and similar color changes, but dedicated primer provides better adhesion and coverage for challenging projects.