Paint Coverage Calculator
Calculate how much paint you need for your painting project. Enter your room dimensions, number of doors and windows, and surface type to get accurate paint quantity, cost estimates, and time requirements.
2 × (Length + Width) × Height
Paintable Area:
Wall Area - (Doors × 21 sq ft) - (Windows × 15 sq ft)
Paint Coverage per Gallon:
• Smooth Surface: 350 sq ft/gallon
• Textured: 300 sq ft/gallon
• Rough (Brick/Stucco): 250 sq ft/gallon
Gallons Needed:
(Paintable Area × Number of Coats) ÷ Coverage per Gallon
Room Dimensions:
• Length: 15 feet
• Width: 12 feet
• Height: 8 feet
• Doors: 2
• Windows: 2
• Coats: 2
• Surface: Smooth
Calculation:
Wall Area: 2 × (15 + 12) × 8 = 432 sq ft
Door Area: 2 × 21 = 42 sq ft
Window Area: 2 × 15 = 30 sq ft
Paintable Area: 432 - 42 - 30 = 360 sq ft
Total with 2 coats: 360 × 2 = 720 sq ft
Gallons: 720 ÷ 350 = 2.06 gallons
Results:
• Area: 360 sq ft
• Paint: 2.25 gallons (rounded up)
• Cost: ~$68
• Time: ~5 hours
How much paint do I need for a 12x12 room?
For a 12×12 room with 8-foot ceilings and 2 coats, you need about 2 gallons of paint. This covers approximately 384 sq ft of wall area (2×(12+12)×8 = 384). One gallon covers 350-400 sq ft, so 2 coats = 768 sq ft ÷ 350 = 2.2 gallons. Buy 2.5 gallons to account for doors, windows, and touch-ups.
How many coats of paint should I apply?
Most walls need 2 coats for even coverage and durability. Use 1 coat only when painting the same color over well-primed surfaces. Use 3 coats when: covering dark colors with light, painting over red/orange, or using low-quality paint. Primer + 2 finish coats is ideal for new drywall or color changes.
How much area does a gallon of paint cover?
One gallon typically covers 350-400 sq ft on smooth surfaces (drywall). Textured surfaces: 300-350 sq ft. Rough surfaces (brick, stucco): 250-300 sq ft. Porous surfaces absorb more paint. High-quality paint covers better than cheap paint. Always buy 10% extra for touch-ups and waste.
Should I subtract doors and windows from paint calculations?
Yes, subtract doors and windows to avoid buying too much paint. Average door = 21 sq ft, standard window = 15 sq ft. However, buy 10% extra anyway for: cutting in around trim, touch-ups, spills, and future repairs. Leftover paint is better than running short mid-project.
🔗 Related Calculators
📐 Formula
2 × (Length + Width) × Height
Paintable Area:
Wall Area - (Doors × 21 sq ft) - (Windows × 15 sq ft)
Paint Coverage per Gallon:
• Smooth Surface: 350 sq ft/gallon
• Textured: 300 sq ft/gallon
• Rough (Brick/Stucco): 250 sq ft/gallon
Gallons Needed:
(Paintable Area × Number of Coats) ÷ Coverage per Gallon
📝 Example Calculation
Room Dimensions:
• Length: 15 feet
• Width: 12 feet
• Height: 8 feet
• Doors: 2
• Windows: 2
• Coats: 2
• Surface: Smooth
Calculation:
Wall Area: 2 × (15 + 12) × 8 = 432 sq ft
Door Area: 2 × 21 = 42 sq ft
Window Area: 2 × 15 = 30 sq ft
Paintable Area: 432 - 42 - 30 = 360 sq ft
Total with 2 coats: 360 × 2 = 720 sq ft
Gallons: 720 ÷ 350 = 2.06 gallons
Results:
• Area: 360 sq ft
• Paint: 2.25 gallons (rounded up)
• Cost: ~$68
• Time: ~5 hours