Paint Coverage Calculator
Paint Needed
2 gallons
333 sq ft paintable area • 2 coats • 375 sq ft/gallon coverage
Gross Wall Area
384 sq ft
Openings Deducted
51 sq ft
Total Coverage Needed
666 sq ft
Estimated Paint Cost
$60 – $100
Doors (1 × 21 sq ft)
21 sq ft
Windows (2 × 15 sq ft)
30 sq ft
Coverage Tip: Eggshell paint covers 375 sq ft per gallon on smooth, primed surfaces. Textured walls, porous surfaces, or drastic color changes can reduce coverage by 20–30%. Always buy 1 extra gallon for touch-ups.
Second Coat Note: The second coat typically provides better coverage than the first because the surface is already sealed. Allow 2–4 hours of drying time between coats for latex paint, or 24 hours for oil-based paint.
Disclaimer: Estimates are for budgeting purposes only. Actual costs vary by location, contractor, material availability, and project complexity. Always get professional quotes for exact pricing.
Paint Coverage Rates by Finish
| Paint Finish | Coverage / Gallon | Cost / Gallon | Best For |
|---|---|---|---|
| Flat / Matte | ~400 sq ft | $25 – $40 | Ceilings, low-traffic rooms |
| Eggshell | ~375 sq ft | $30 – $50 | Living rooms, bedrooms |
| Satin | ~350 sq ft | $30 – $50 | Family rooms, hallways, kids rooms |
| Semi-Gloss | ~325 sq ft | $35 – $55 | Kitchens, bathrooms, trim |
| Gloss | ~300 sq ft | $40 – $70 | Doors, cabinets, trim |
Paint Needed by Room Size (2 Coats, Eggshell)
| Room | Dimensions | Paintable Area | Gallons Needed | Estimated Cost |
|---|---|---|---|---|
| Bedroom | 12 × 12 × 8 ft | 333 sq ft | 2 gallons | $60 – $100 |
| Living Room | 15 × 20 × 8 ft | 473 sq ft | 3 gallons | $90 – $150 |
| Bathroom | 8 × 10 × 8 ft | 252 sq ft | 2 gallons | $60 – $100 |
| Kitchen | 12 × 14 × 9 ft | 417 sq ft | 3 gallons | $90 – $150 |
Factors That Reduce Paint Coverage
| Factor | Coverage Reduction | Solution |
|---|---|---|
| Textured Walls | 15% – 25% less | Add 1 extra gallon per 2–3 rooms |
| Unprimed Surfaces | 20% – 40% less | Apply primer coat first ($15–$25/gal) |
| Dark-to-Light Change | Requires 3 coats | Use tinted primer to reduce coats |
| Spray Application | 20% – 30% more paint | Use roller for walls, spray for trim |
How We Calculate
Our paint coverage calculator estimates how much paint you need based on exact room dimensions, paint finish type, number of coats, and door/window deductions. Unlike our general paint calculator (which uses wall count × average length), this tool computes wall area from room length and width for a more precise per-room estimate.
How the math works: We calculate wall perimeter as 2 × (length + width), then multiply by ceiling height for gross wall area. Standard door openings (21 sq ft each) and window openings (15 sq ft each) are subtracted. The paintable area is multiplied by the number of coats, then divided by the coverage rate for your selected paint finish to determine gallons needed (rounded up to the nearest whole gallon).
Paint Coverage by Finish Type
Flat / Matte covers ~400 sq ft per gallon. The highest coverage rate because flat paint maximizes pigment content. Best for ceilings and low-traffic rooms where washability is not a concern.
Eggshell covers ~375 sq ft per gallon. The most popular finish for living spaces, offering a subtle sheen that is easier to clean than flat paint while still hiding minor wall imperfections.
Satin covers ~350 sq ft per gallon. A versatile, slightly glossy finish that resists moisture and stains. Ideal for family rooms, hallways, and children’s rooms where walls need regular cleaning.
Semi-Gloss covers ~325 sq ft per gallon. Durable and moisture-resistant, making it the standard choice for kitchens, bathrooms, and trim work. Shows wall imperfections more than lower-sheen finishes.
Gloss covers ~300 sq ft per gallon. The most durable and reflective finish with the lowest coverage rate. Best reserved for doors, cabinets, and accent trim where you want maximum sheen and washability.
Factors That Reduce Coverage
Our calculator assumes smooth, primed surfaces. Real-world coverage may be lower due to: textured walls (knockdown, orange peel, or popcorn textures absorb 15–25% more paint), porous surfaces (unprimed drywall, bare wood, or masonry reduce coverage by 20–40%), dark-to-light color changes (may require 3 coats or a tinted primer coat first), and application method (spraying uses 20–30% more paint than rolling due to overspray).
Data Sources
Coverage rates and pricing are compiled from manufacturer specifications (Benjamin Moore, Sherwin-Williams, Behr, PPG), HomeAdvisor, Angi, and retail pricing at Home Depot and Lowe’s. We review and update this data regularly to reflect current market conditions.
Last updated: 2026-02-08
Frequently Asked Questions
How much does a gallon of paint cover? +
One gallon of paint covers 300–400 square feet depending on the finish. Flat/matte paint covers the most at ~400 sq ft/gallon, eggshell covers ~375 sq ft, satin ~350 sq ft, semi-gloss ~325 sq ft, and gloss ~300 sq ft. These figures assume smooth, primed surfaces with one coat. Textured walls, porous surfaces, and dark-to-light color changes reduce coverage by 20–30%.
Why does paint finish affect coverage per gallon? +
Higher-sheen paints (semi-gloss, gloss) contain more resins and fewer pigment solids than flat or eggshell paints. Resins create the shiny, durable surface but spread less efficiently, reducing coverage to 300–325 sq ft per gallon. Flat paints maximize pigment content, covering up to 400 sq ft per gallon. This is why gloss paint costs more per square foot of coverage than flat paint.
How do I calculate paintable wall area for a room? +
Measure room length and width in feet. Calculate wall perimeter: 2 × (length + width). Multiply perimeter by ceiling height to get gross wall area. Then subtract openings: 21 sq ft per standard door (3×7 ft) and 15 sq ft per standard window (3×5 ft). The result is your paintable wall area. For example, a 12×12 room with 8 ft ceilings, 1 door, and 2 windows: 2 × (12+12) × 8 = 384 sq ft − 21 − 30 = 333 sq ft paintable area.
How many coats of paint do I need for good coverage? +
Two coats is the standard recommendation for most painting projects. One coat may be sufficient when repainting the same color or using premium paint-and-primer-in-one products. Three coats are needed when painting over dark colors with light paint, covering stains, or using bold/deep colors with poor hiding power. Always follow the manufacturer’s recommendation on the paint can.
Does primer affect paint coverage? +
Yes, primer significantly improves paint coverage. On unprimed drywall, bare wood, or patched surfaces, paint soaks into the porous material and coverage drops to 200–250 sq ft per gallon. A coat of primer ($15–$25/gallon) seals the surface so your topcoat achieves full coverage at 300–400 sq ft per gallon. Tinted primer is especially helpful when making drastic color changes.
How much paint do I need for a 12x12 room? +
A 12×12 room with 8 ft ceilings has 384 sq ft of gross wall area. After subtracting 1 door (21 sq ft) and 2 windows (30 sq ft), you have 333 sq ft of paintable area. With 2 coats of eggshell paint (375 sq ft/gallon coverage), you need approximately 2 gallons. Buy an extra gallon for touch-ups, so plan on 3 gallons total.
What is the difference between the Paint Calculator and the Paint Coverage Calculator? +
The Paint Calculator uses a walls × average wall length approach and focuses on total paint cost estimation. The Paint Coverage Calculator uses exact room dimensions (length × width × height) and emphasizes how different paint finishes affect coverage rates per gallon. Use the Coverage Calculator when you want to understand how finish choice impacts the amount of paint needed.
Should I buy extra paint beyond what the calculator shows? +
Yes, always purchase 1 extra gallon beyond the calculated amount. This covers touch-ups, color matching for future repairs, and any areas where you need an extra coat. Store leftover paint sealed at room temperature and label the can with the room name, color code, and date. Paint batches can vary slightly in color, so having matching paint is valuable.
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