Paint Calculator

Welcome to the Paint Calculator, a comprehensive tool designed to help DIYers, homeowners, and professional painters accurately estimate paint quantities for any room. Whether you're refreshing a single bedroom or tackling a whole-house repaint, this calculator accounts for walls, ceilings, trim, doors, windows, and surface texture to give you precise gallon or liter estimates.

How to Use the Paint Calculator

1. Enter Room Dimensions: Input the length, width, and height of your room in feet or meters.
2. Count Openings: Enter the number of doors and windows - their area will be automatically deducted.
3. Select Options: Choose whether to include ceiling and/or trim paint, number of coats, and wall texture type.
4. Calculate: Click the calculate button to see your paint estimate with shopping recommendations.

Understanding Paint Coverage

Paint coverage refers to how much surface area a gallon or liter of paint can cover. Standard interior latex paint typically covers:

Paint Calculation Formula

Texture Adjustment Factors

Different wall textures have more surface area and absorb more paint:

• Smooth (1.0×): Standard drywall or plaster - no adjustment needed
• Light Texture (1.1×): Orange peel finish - 10% more paint
• Medium Texture (1.25×): Knockdown or skip trowel - 25% more paint
• Heavy Texture (1.5×): Popcorn ceiling or stucco - 50% more paint

How Many Coats Do You Need?

The number of coats depends on several factors:

• Same or similar color: 1-2 coats usually sufficient
• Light over light: 2 coats for even coverage
• Light over dark: 2-3 coats (consider primer first)
• Dark or vibrant colors: 2-3 coats (reds, yellows, oranges cover poorly)
• New drywall: 1 coat primer + 2 coats paint

Professional Painting Tips

• Buy 10-15% extra: Account for touch-ups, mistakes, and future repairs
• Same batch numbers: Buy all paint at once to ensure color consistency
• Quality matters: Premium paints often have better coverage and durability
• Proper prep: Clean walls, fill holes, and prime when necessary
• Test first: Paint a sample area to verify color before committing

Standard Door and Window Sizes

This calculator uses industry-standard sizes for deductions:

• Standard door: 20 sq ft (3' × 6'8") or 1.86 m² (0.9m × 2.1m)
• Standard window: 15 sq ft (3' × 5') or 1.4 m² (1m × 1.4m)

Frequently Asked Questions

How much paint do I need for a 12x12 room?

For a standard 12×12 foot room with 8-foot ceilings, one door, and two windows, you'll need approximately 1.5-2 gallons of paint for two coats on the walls only. This assumes smooth walls and standard coverage of 350 sq ft per gallon. Add about 0.5 gallon per coat (≈1 gallon for two coats) if you're also painting the ceiling.

How many square feet does 1 gallon of paint cover?

One gallon of paint typically covers 350-400 square feet on smooth surfaces. However, coverage varies based on surface texture, paint quality, application method, and whether you're making a significant color change.

Should I subtract doors and windows when calculating paint?

Yes, subtracting doors and windows gives you a more accurate estimate and prevents over-buying. A standard door takes up about 20 square feet, and a typical window about 15 square feet.

How many coats of paint do I need?

Most painting projects require 2 coats for optimal coverage and durability. You may need only 1 coat for touch-ups with the same color, or 3+ coats when covering dark colors with light ones.

Does textured wall require more paint?

Yes, textured walls require more paint due to increased surface area. Light texture needs about 10% more, medium texture about 25% more, and heavy texture can require up to 50% more paint.