Paint Calculator
Estimate the amount of paint you need for any room. Enter room dimensions, number of doors and windows, paint coverage, and get the number of paint cans required, including waste factor and multiple coats.
📊 Paint Coverage Reference
| Surface Type | Coverage (sq ft/gal) | Notes |
|---|---|---|
| Smooth Drywall | 350-400 | Standard coverage |
| Textured Drywall | 250-350 | More paint needed |
| Brick / Masonry | 150-250 | Highly absorbent |
| Wood (painted) | 300-400 | Similar to drywall |
| Wood (raw) | 200-300 | Needs primer + paint |
| Ceiling (smooth) | 350-400 | Use ceiling paint |
| Ceiling (textured) | 250-350 | More paint needed |
How Paint Calculations Work
This calculator estimates the amount of paint you need for any room. It calculates the total paintable area by summing the wall area and ceiling area (if selected), then subtracting the area taken up by doors, windows, and other custom exclusions.
Wall Area = 2 × (Length + Width) × Height
Ceiling Area = Length × Width
Total Area = Wall Area + Ceiling Area − Subtractions
Gallons Needed = (Total Area × Coats × (1 + Waste Factor)) ÷ Coverage
Cans Needed = Ceiling(Gallons Needed)
Total Cost = Cans Needed × Price per Gallon
For example: A 12ft × 10ft room with 8ft ceilings has:
- Wall Area = 2 × (12 + 10) × 8 = 352 sq ft
- Ceiling Area = 12 × 10 = 120 sq ft
- Total = 472 sq ft − doors/windows (e.g., 1 door × 20 sq ft + 2 windows × 15 sq ft = 50 sq ft) = 422 sq ft
- With 2 coats and 10% waste: 422 × 2 × 1.1 = 928 sq ft
- At 350 sq ft/gallon: 928 ÷ 350 = 2.65 gallons → 3 cans needed
Tips for Estimating Paint
- Always Buy Extra: A 10% waste factor accounts for spills, mistakes, and touch-ups. It's better to have extra paint for future repairs.
- Consider Primer: New drywall, bare wood, or dark colors may need a primer coat before painting. Factor this into your coat count.
- Check Coverage: Different paint brands and finishes have different coverage rates. Check the label on your paint can.
- Texture Matters: Textured walls and ceilings absorb more paint. Increase your coverage estimate by 20-30% for heavy textures.
- Color Changes: Painting over a dark color with a light color may require an extra coat or primer for full coverage.
❓ Paint Calculator FAQ
How much paint do I need for a 12x12 room?
A 12×12 room with 8ft ceilings has about 384 sq ft of wall area and 144 sq ft of ceiling area. After subtracting doors and windows, you'll need about 400-500 sq ft of paintable area. With 2 coats, you'll need 2-3 gallons of paint.
How many square feet does a gallon of paint cover?
A gallon of paint typically covers 350-400 square feet on smooth surfaces. Textured surfaces may require more paint, covering 250-350 square feet per gallon.
How do I calculate paint for a room?
Measure the length, width, and height of the room. Calculate wall area: 2 × (Length + Width) × Height. Calculate ceiling area: Length × Width. Subtract doors (≈20 sq ft each) and windows (≈15 sq ft each). Multiply by the number of coats and waste factor, then divide by the coverage per gallon.
What is the standard coverage for paint?
The standard coverage for paint is 350-400 square feet per gallon on smooth surfaces. This varies by brand, finish, and surface texture. Always check the label on your paint can for the manufacturer's coverage estimate.
How much does it cost to paint a room?
DIY painting costs typically range from $50-200 for materials (paint, primer, brushes, rollers, tape). Professional painting costs $300-800 per room on average. This calculator helps you estimate material costs for your project.
How many coats of paint do I need?
Most rooms need 2 coats of paint for full coverage. If you're painting over a similar color, 1 coat may be sufficient. Painting over dark colors or bare surfaces typically requires 2-3 coats or a primer coat.
What is the waste factor for paint?
A waste factor of 10-15% is recommended to account for spills, mistakes, and touch-ups. This ensures you have enough paint to complete the job without running short.
How do I calculate paint for a ceiling?
Ceiling area = Room Length × Room Width. Multiply by the number of coats and waste factor, then divide by the coverage per gallon. The calculator includes an option to include the ceiling.
How much paint do I need for a 10x10 room?
A 10×10 room with 8ft ceilings has about 320 sq ft of wall area and 100 sq ft of ceiling area. After subtracting doors and windows, you'll need about 350-400 sq ft of paintable area. With 2 coats, you'll need 2 gallons of paint.
What is the difference between flat, satin, and gloss paint?
Flat paint has no shine and hides imperfections well. Satin paint has a slight sheen and is easier to clean. Gloss paint is shiny and very durable. Coverage is similar across finishes, but some may require more coats.
How do I calculate paint for a room with sloped ceilings?
For sloped ceilings, measure the width and height of each wall section separately. Calculate the area of each section and add them together. This calculator assumes standard rectangular rooms.
Do I need primer before painting?
Primer is recommended for new drywall, bare wood, previously unpainted surfaces, dark colors, and water stains. Primer improves adhesion and coverage. If you're painting over a similar color, you may not need primer.
How do I calculate paint for trim and baseboards?
Measure the length of each piece of trim, multiply by the width, and sum the areas. Trim typically requires less paint than walls. This calculator focuses on walls and ceilings.
What is the average cost of paint per gallon?
Paint costs vary widely by brand and quality. Budget paint starts at $15-25 per gallon, mid-range paint is $30-50 per gallon, and premium paint can cost $60-100+ per gallon. This calculator uses the price you enter.
How do I know if I have enough paint?
Always buy slightly more than you calculate. You can return unopened cans to most stores. It's better to have extra paint for touch-ups than to run out mid-project.
How long does it take for paint to dry?
Paint drying time varies by type and conditions. Latex paint dries in 1-2 hours and is ready for a second coat in 2-4 hours. Oil-based paint takes 6-8 hours to dry and 24 hours for a second coat. Always check the manufacturer's recommendations.
What is the best paint for a bathroom?
Bathrooms need moisture-resistant paint. Use satin, semi-gloss, or gloss finishes with mildew-resistant properties. These are more durable and easier to clean in humid environments.
How much paint do I need for a 2,000 sq ft house?
A 2,000 sq ft house typically requires 10-15 gallons of paint for the interior walls, depending on the number of rooms and ceilings. This calculator helps you calculate room by room for precise estimates.