Paint Calculator
Calculate exactly how much paint you need for your project. Account for walls, ceilings, trim, doors, windows, and multiple coats. Save money by avoiding over-purchasing while ensuring complete coverage.
Room Dimensions
Openings
Standard door: 20 sq ft
Standard window: 15 sq ft
Paint Settings
Assumes 6-inch (0.5 ft) trim height
Cost Estimation (Optional)
Comprehensive Coverage
Calculate paint for walls, ceilings, trim, doors, and windows with accurate formulas.
Cost Estimation
Input paint costs and get instant total project cost estimates for budgeting.
100% Private
All calculations happen in your browser. Your data never leaves your device.
How to Use
Measure Your Room
Enter the length, width, and height of your room in feet. Measure from wall to wall for accuracy.
Count Doors and Windows
Enter the number of standard doors (20 sq ft each) and windows (15 sq ft each) in the room.
Configure Paint Settings
Select number of coats (1-3), coverage rate based on surface type, and optionally include ceiling and trim.
Get Results
Click calculate to see exactly how many gallons you need, with optional cost estimation if you enter paint price.
Frequently Asked Questions
How much paint coverage can I expect per gallon?
Typical interior latex paint covers 350-400 sq ft per gallon in one coat. Exterior paint is similar (300-400 sq ft/gallon). Primers cover 200-300 sq ft/gallon. Glossy finishes cover less (300-350) than matte (350-400) due to application differences. Multiple coats, dark colors, textured surfaces, and new drywall reduce coverage. Our calculator uses standard rates but lets you adjust based on conditions.
How many coats of paint do I need?
Standard: 2 coats for most interior projects provides good coverage and durability. Fresh drywall/new surfaces may need 3 coats for even color. Primer is recommended for: bare drywall, stains, odor, color changes, glossy surfaces. Primer + 1 coat can work for minor touch-ups. Our calculator lets you specify number of coats.
How do I measure my room for paint calculation?
Measure wall height and width, calculate area = height × width. Add areas of all walls to get total wall area. For ceiling, measure length × width. Subtract window and door areas (rough estimate ~20 sq ft each). Example: 10ft × 12ft room, 8ft ceiling = 2(10×8) + 2(12×8) - 2(20) = 320 sq ft walls + 120 sq ft ceiling = 440 sq ft total.
Should I buy extra paint?
Yes, always buy 10-15% extra paint for: touch-ups (during and after painting), color matching for future repairs, waste from spills/roller absorption. Since paint formulas vary between batches, buying extra ensures color consistency. Keep paint in cool dry storage for years. Small cans (quarts) are good for touch-ups; larger cans are more economical for main coats.
What factors reduce paint coverage?
Rough/textured surfaces, porous materials (new drywall, wood), dark colors (need extra coats), glossy finishes, humidity and temperature extremes, applicator skill, and old paint with stains. Budget extra paint if: surface is textured, painting dark color over light (vice versa), surface is porous, or applying primer. Our calculator lets you adjust coverage for these conditions.
Is my data private?
Yes! All calculations happen in your browser. Your data is never sent to any server, ensuring complete privacy and security.