Paint Calculator – Gallons Needed for Any Room
Calculate gallons of paint needed for walls, ceilings, or any surface.
About This Calculator
Calculate gallons of paint needed for walls, ceilings, or any surface. Use the calculator above for instant results.
Worked Examples
- Total: 1,000 sq ft | 2.86 gallons → buy 3 gallons
Answer: 3 gallons
- Walls: 630 sq ft | Total: 1,260 sq ft → 3.6 gallons → buy 4
Answer: 4 gallons
- 150 sq ft / 350 = 0.43 gallons → buy 1 quart
Answer: 1 quart (0.43 gal)
Who Uses This Calculator?
Buy exact paint quantity.
Estimate paint for bids.
Budget renovation costs.
Avoid buying too much or little paint.
Common Mistakes to Avoid
❌ Using exact calculated amount
Always round UP and add 10% for trim errors and touch-ups. Running out mid-wall is worse than having extra.
❌ Not subtracting doors and windows
Each standard door = ~20 sq ft, window ~15 sq ft. Subtract for large rooms with many openings.
Frequently Asked Questions
Coverage rate?
Most interior paints: 350-400 sq ft per gallon. Premium paints often cover better. Check the can label.
How many coats?
New paint over old: 1-2 coats. Dramatic color change: 2-3 coats. Over primer: 2 coats.
Primer needed?
Yes for new drywall, major color changes, or stains. Primer improves adhesion and coverage, often saving paint.