Understanding Paint Coverage
Buying the right amount of paint saves money and multiple trips to the store. Most interior paints cover 350-400 square feet per gallon, but actual coverage depends on wall texture, porosity, and color change.
What affects coverage:
- Wall texture: Smooth walls need less paint; textured walls absorb more
- Paint quality: Premium paints cover better and need fewer coats
- Color change: Dark to light (or vice versa) requires extra coats
- Surface prep: Primed surfaces cover better than bare drywall
- Application method: Spraying uses more paint than brush/roller
Paint Sheen Guide
| Sheen | Best For | Durability |
|---|---|---|
| Flat/Matte | Ceilings, low-traffic areas, hiding imperfections | ★☆☆☆ |
| Eggshell | Living rooms, bedrooms, dining rooms | ★★☆☆ |
| Satin | Hallways, kids rooms, family rooms | ★★★☆ |
| Semi-Gloss | Kitchens, bathrooms, trim, doors | ★★★★ |
| High-Gloss | Trim, cabinets, doors, high-moisture areas | ★★★★ |
Rule of thumb: Higher sheen = more durable & easier to clean, but shows imperfections more.
When Do You Need Primer?
✅ Use Primer When:
- New/bare drywall
- Dark to light color change
- Covering stains or smoke damage
- Painting over glossy surfaces
- Wood surfaces (especially tannin-rich wood)
- Previously wallpapered walls
⏭️ Skip Primer When:
- Repainting same or similar color
- Using paint + primer combo
- Previously painted, clean surfaces
- Light to dark color change
Tip: Self-priming paints work for most repaints, but dedicated primer is better for problem surfaces.
How to Calculate Paint Needed
Step-by-step formula:
1. Wall Area = Perimeter × Height
2. Subtract openings: Doors (~21 sq ft each), Windows (~15 sq ft each)
3. Paintable Area = Wall Area - Openings
4. Gallons = (Paintable Area × Number of Coats) ÷ 350
Pro tips:
- Always round up to the next full gallon
- Buy extra quart for touch-ups later
- Ceiling area = room length × room width
Example: 12×14 ft Bedroom
Scenario: 12×14 ft bedroom with 8 ft ceilings, 2 windows, 1 door. Applying 2 coats.
- Perimeter: (12 + 14) × 2 = 52 linear feet
- Wall area: 52 × 8 = 416 sq ft
- Subtract openings: 2 windows (30) + 1 door (21) = 51 sq ft
- Paintable area: 416 - 51 = 365 sq ft
- With 2 coats: 365 × 2 = 730 sq ft coverage needed
- Gallons: 730 ÷ 350 = 2.09 → 3 gallons (round up)
Result: Buy 3 gallons of wall paint. Add 1 gallon for the ceiling and 1 quart for trim.