Paint Coverage Calculator
Calculate how much paint you need for your walls and rooms. Includes multiple coats and gallons needed.
How to Calculate Paint Coverage
Calculating paint needs saves money and ensures you have enough to complete your project. This calculator determines gallons needed based on room dimensions and number of coats. One gallon typically covers 350-400 square feet with one coat, though coverage varies by paint quality, surface texture, and application method.
Paint Coverage Formula
- Calculate wall area: 2 × (Length + Width) × Height
- Subtract doors and windows (optional): -20 sq ft per door, -15 sq ft per window
- Multiply by number of coats
- Divide by coverage per gallon (350-400 sq ft)
- Round up to nearest gallon
Coverage by Paint Type
- Flat/Matte: 400-450 sq ft/gallon (best coverage)
- Eggshell: 350-400 sq ft/gallon
- Satin: 350-400 sq ft/gallon
- Semi-Gloss: 350-400 sq ft/gallon
- High-Gloss: 300-350 sq ft/gallon (least coverage)
- Primer: 200-300 sq ft/gallon
Example Calculations
Standard Bedroom (12' × 12', 8' ceiling)
Wall area: 2 × (12 + 12) × 8 = 384 sq ft
Two coats: 384 × 2 = 768 sq ft
Paint needed: 768 / 350 = 2.2 gallons → Buy 3 gallons
Living Room (20' × 15', 9' ceiling)
Wall area: 2 × (20 + 15) × 9 = 630 sq ft
Two coats: 630 × 2 = 1,260 sq ft
Paint needed: 1,260 / 350 = 3.6 gallons → Buy 4 gallons
Paint Sizes and Costs
- Quart: Covers ~100 sq ft, $10-15 (touch-ups, small projects)
- Gallon: Covers ~350 sq ft, $25-50 (standard room)
- 5-Gallon Bucket: Covers ~1,750 sq ft, $100-200 (whole house, best value)
Primer Guidelines
Use primer when:
- Painting new drywall (bare walls absorb paint)
- Covering dark colors with light colors
- Painting over stains (water, smoke, grease)
- Dramatic color change (red to white, etc.)
- Painting glossy surfaces (helps paint adhere)
- Preventing bleed-through (wood knots, markers)
Primer coverage: 200-300 sq ft/gallon
Allows topcoat to go further (may only need 1-2 coats vs 3-4 without primer)
Paint Application Tips
Preparation (Most Important Step)
- Clean walls thoroughly
- Repair holes and cracks with spackle
- Sand rough spots smooth
- Remove or cover furniture
- Tape trim, edges, ceiling
- Lay drop cloths
Painting Technique
- Cut in: Brush edges, corners, trim first
- Roll: Use roller for large wall areas
- W pattern: Roll in W shape, then fill in
- Wet edge: Keep edge wet to avoid lap marks
- Thin coats: Multiple thin coats better than one thick coat
- Dry time: Wait 2-4 hours between coats (check label)
Paint Quality Matters
Budget Paint ($15-25/gallon)
Lower pigment concentration, requires more coats, shorter lifespan (3-5 years)
Mid-Range Paint ($30-45/gallon)
Good coverage, decent durability, standard choice for most projects
Premium Paint ($50-80/gallon)
Excellent coverage, may only need one coat, lasts 10+ years, easier application, better color retention
Cost comparison: Cheap paint needs 3 coats (3 gallons × $20 = $60) vs premium needs 1 coat (1 gallon × $50). Premium often saves money!
Paint Finish Selection
By Room
- Bedrooms: Matte or eggshell (soft, non-reflective)
- Living rooms: Eggshell or satin (some sheen, washable)
- Kitchens: Satin or semi-gloss (easy to clean)
- Bathrooms: Semi-gloss or high-gloss (moisture resistant)
- Trim/Doors: Semi-gloss (durable, wipeable)
- Ceilings: Flat (hides imperfections)
By Sheen
- Flat/Matte: No shine, hides imperfections, hard to clean
- Eggshell: Slight sheen, some washability
- Satin: Soft sheen, very washable, most versatile
- Semi-Gloss: Noticeable sheen, very durable
- High-Gloss: Mirror-like finish, extremely durable
Common Painting Mistakes
- Skipping primer: Results in poor coverage, more coats needed
- Cheap paint: Requires extra coats, doesn't last
- Poor prep: Paint highlights flaws rather than hiding them
- Too thick: Drips, runs, uneven finish
- Rushing: Not allowing proper dry time between coats
- Bad brush/roller: Cheap tools shed bristles, leave texture
- Wrong finish: Flat paint in kitchen, glossy in bedroom
Tools Needed
- Paint roller + extension pole
- Roller covers (nap depth based on texture)
- 2-3 inch angled brush for cutting in
- Paint tray with liner
- Painter's tape (blue for walls, green for delicate)
- Drop cloths (canvas better than plastic)
- Stir sticks
- Spackle and putty knife
- Sandpaper (120-150 grit)
Pro Tip: Buy all paint needed from same batch! Colors can vary slightly between batches. Mix all paint together in one bucket (called "boxing") before starting to ensure consistent color throughout the project.