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Paint Cost Calculator

Calculate total paint cost for your room including gallons needed.

Last updated: June 13, 2026

Calculator

feet
feet
feet
$/gal
coats

Results

Gallons Needed3
Total Cost$105
Wall Area416 sq ft
Coverage Area707 sq ft (2 coats)

How to Use This Calculator

  1. 1Enter room length and width.
  2. 2Enter ceiling height.
  3. 3Enter paint price per gallon.
  4. 4Enter number of coats.
  5. 5View gallons needed and total cost.

Formula Explanation

Paint coverage is approximately 350 sq ft per gallon. Wall area is calculated from perimeter and height, minus 15% for windows/doors.

Wall Area = 2×(L+W) × Height × 0.85 Gallons = (Wall Area × Coats) ÷ 350

Variables:

L, WRoom dimensions in feet
HeightCeiling height
350Average sq ft coverage per gallon

Worked Examples

14×12 ft room, 8ft ceilings, $35/gal, 2 coats

  1. 1. Wall area = 2×(14+12)×8 = 416 sq ft
  2. 2. Adjusted (85%): 354 sq ft
  3. 3. With 2 coats: 707 sq ft
  4. 4. Gallons = 707/350 = 2.02 → 3 gallons
Result: 3 gallons needed, $105 total

Why Use This Calculator

  • Know exactly how much paint to buy.
  • Budget accurately for your project.
  • Avoid multiple trips to the store.
  • Accounts for windows and doors.
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Tips & Best Practices

  • One gallon of paint covers approximately 350-400 sq ft on smooth surfaces.
  • Textured walls and dark-to-light color changes may need 3 coats.
  • Buy all paint from the same batch for consistent color.
  • Keep leftover paint for touch-ups — label cans with room and date.

Common Mistakes to Avoid

Buying too little paint and running out mid-wall.

Always round up to the next full gallon. It's better to have leftover paint for future touch-ups than to run out and risk color mismatch.

Not accounting for the number of coats.

Most paint jobs need 2 coats. Going from dark to light may require a primer plus 2 coats.

Frequently Asked Questions

How much does a gallon of paint cover?
Average coverage is 350-400 sq ft per gallon on smooth, primed walls. Rough or porous surfaces may only get 250-300 sq ft per gallon.
How much does it cost to paint a room?
DIY paint cost for a 12×12 room is $60-200 for paint alone. Professional painting runs $300-800 per room including labor.
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Disclaimer: This calculator is provided for informational and educational purposes only. Results are estimates and should not be used as a substitute for professional advice. RediCalc.com makes no guarantees regarding the accuracy, completeness, or suitability of any calculations. Always consult a qualified professional before making financial, health, construction, or other important decisions.

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