Last updated: 2026-02-13
Quick Answer
Most rooms take 1–3 gallons of paint per coat depending on wall area and surface texture. A common planning number is 350–400 sq ft per gallon on smooth, primed walls (less on textured or porous surfaces). Measure your paintable area, multiply by the number of coats (2 is typical), then divide by your coverage rate and round up.
Inputs you’ll need
- Room length, width, and ceiling height (feet)
- Number of doors and windows (to subtract non-paintable area)
- Coats (1–3) and surface type (smooth vs. textured/porous)
- Optional: ceiling paint, trim/door paint, and primer
How to use this paint calculator
- Enter your room dimensions and ceiling height.
- Subtract doors and windows for a tighter wall-area number.
- Select coats and texture/porosity assumptions (coverage per gallon).
- Review gallons needed (rounded up) and the cost range.
Before you buy paint (quick checklist)
- Add 10–15% overage for waste and touch-ups.
- Buy all gallons for a room at once (same batch) to avoid slight color shifts.
- Plan on primer for new drywall, stains, drastic color changes, or glossy surfaces.
- Textured walls and bare surfaces usually need more paint than the label suggests.
Typical coverage assumptions (rules of thumb)
| Surface | Planning coverage (sq ft / gal) | Notes |
|---|---|---|
| Smooth, primed drywall | 350–400 | Best-case coverage |
| New drywall / porous surface | 300–350 | Primer helps finish paint go further |
| Light texture (orange peel / knockdown) | 250–300 | Extra surface area eats paint |
| Heavy texture | 200–250 | Plan higher waste/overage |
Worked examples (with the math)
Example A (walls): 12×12 room, 8 ft ceilings, 1 door, 2 windows, 2 coats, 375 sq ft/gal
- Wall area = 2 × (12 + 12) × 8 = 384 sq ft
- Subtract openings = (1 × 20) + (2 × 15) = 50 sq ft
- Paintable area = 384 − 50 = 334 sq ft
- Total coverage needed = 334 × 2 coats = 668 sq ft
- Gallons = 668 ÷ 375 = 1.78 → round up to 2 gallons (then add 10–15% overage if desired)
Example B (textured walls + ceiling): Same room, light texture (275 sq ft/gal), plus ceiling (2 coats)
- Textured wall gallons = (668 ÷ 275) = 2.43 → 3 gallons
- Ceiling area = 12 × 12 = 144 sq ft; 2 coats = 288 sq ft
- Ceiling gallons (at 375 sq ft/gal) = 288 ÷ 375 = 0.77 → 1 gallon
- Planning total: 3 gallons (walls) + 1 gallon (ceiling) = 4 gallons (before trim/doors adders)
If you also need labor pricing, use the painting estimate calculator. For tricky layouts, sanity-check measurements with the square footage calculator.
Room 1
Paint Coverage & Cost Guide
Gallons per room, cost tiers, coat recommendations, and DIY vs. professional pricing.
How Much Paint Do I Need Per Room?
One gallon of paint covers 350–400 square feet on smooth, primed surfaces. A standard 12×12 room with 8-ft ceilings needs about 2 gallons for 2 coats.
- 10×10 room (8 ft ceilings): ~1.5 gallons for 2 coats
- 12×12 room: ~2 gallons for 2 coats
- 14×14 room: ~2.5 gallons for 2 coats
- Deductions: Subtract 20 sq ft per door, 15 sq ft per window
Textured walls reduce coverage by 20–30% (250–300 sq ft/gallon). Bare drywall absorbs more paint: use a primer coat first.
Key Takeaways
- 1 gallon covers 350–400 sq ft (smooth walls)
- 12×12 room: ~2 gallons for 2 coats
- Textured walls: reduce coverage 20–30%
Paint Costs & Quality Tiers in 2026
Paint prices range from $25–$80+ per gallon, with premium paint offering significantly better coverage and durability.
- Economy/contractor grade: $25–$35/gallon (more coats needed, less washable)
- Mid-range: $35–$50/gallon (good coverage, reasonable durability)
- Premium (Sherwin-Williams, Benjamin Moore): $50–$80/gallon (1-coat coverage, excellent washability)
- Primer: $20–$40/gallon (needed for new drywall, stain-blocking, color changes)
Premium paint often saves money long-term: better coverage means fewer coats, and superior durability means less frequent repainting.
Key Takeaways
- Economy paint: $25–$35/gallon
- Premium paint: $50–$80/gallon (better coverage + durability)
- Premium often cheaper long-term (fewer coats needed)
How Many Coats of Paint Do I Need?
Most projects require 2 coats for even, full coverage. One coat works only for same-color touch-ups with premium paint.
- 1 coat: Same color recoat with premium paint-and-primer combo
- 2 coats: Standard for most color changes and new construction
- 3 coats: Deep reds, yellows, oranges over light colors (low-hiding pigments)
- Primer + 2 coats: Required for new drywall, covering dark colors, or stain-blocking
Key Takeaways
- 2 coats standard for most projects
- Reds/yellows/oranges may need 3 coats
- New drywall: primer + 2 coats
Professional Painting vs. DIY Cost Comparison
Professional interior painting costs $2–$6 per square foot of wall area, while DIY costs $0.50–$1.50/sq ft (materials only).
- DIY cost (materials only): $200–$500 per room
- Professional cost: $400–$1,200 per room (labor + materials)
- Exterior painting (professional): $3,000–$8,000 for a 2,000 sq ft home
- DIY speed: 1 room per day (cut in, 2 coats, cleanup)
- Professional speed: 2–3 rooms per day (experienced crew)
Key Takeaways
- Professional: $2–$6/sq ft of wall area
- DIY materials only: $200–$500 per room
- Exterior painting: $3,000–$8,000 (professional)
How to Use This Calculator
Enter your room dimensions
Input the room length, width, and ceiling height in feet. The calculator computes total wall area automatically from the perimeter.
Subtract doors and windows
Enter the number of doors (20 sq ft each) and windows (15 sq ft each) so the calculator deducts non-paintable areas for an accurate estimate.
Choose coats and paint grade
Select 1 or 2 coats and pick your paint quality tier. Two coats are recommended for most projects, especially color changes.
Review gallons needed and cost
See total gallons of paint needed (rounded up), optional primer, and a complete cost range including supplies like tape and rollers.
Paint Coverage Formulas
Wall Area = 2 × (Length + Width) × Height
Paintable Area = Wall Area − (Doors × 20) − (Windows × 15)
Gallons = (Paintable Area × Coats) / 375Where:
- Length / Width
- = Room dimensions in feet
- Height
- = Ceiling height in feet (typically 8-10 ft)
- 375
- = Average coverage rate in sq ft per gallon (range: 350-400)
- Coats
- = Number of coats — 2 recommended for most projects
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Frequently Asked Questions
How much paint do I need for a 12x12 room?
A standard 12×12 room with 8-foot ceilings has about 384 sq ft of wall area. After subtracting 1 door and 2 windows, you have roughly 334 sq ft of paintable surface. For 2 coats, you need approximately 2 gallons of paint. Always round up to avoid running short mid-wall.
How many square feet does a gallon of paint cover?
One gallon of interior paint covers approximately 350–400 square feet on smooth, primed surfaces. Coverage decreases on textured walls (250–300 sf), bare drywall (300–350 sf), or rough exterior surfaces. Dark colors over light, or vice versa, may require an extra coat for full coverage.
Do I need primer before painting?
Primer is recommended when painting new drywall, covering dark colors with light paint, painting over stains, or switching between oil and latex paint. Self-priming paints work for minor color changes on previously painted walls, but a dedicated primer provides better adhesion and coverage for challenging surfaces.
What is the difference between economy and premium paint?
Premium paints ($50–$80/gallon) contain higher percentages of titanium dioxide and acrylic resins than economy paints ($25–$35/gallon). This means better coverage (often in fewer coats), superior washability, better color retention, and longer-lasting finish. For high-traffic areas like kitchens and hallways, premium paint is the better investment.
How many coats of paint do I need?
Most projects require 2 coats for full, even coverage. You may get away with 1 coat when repainting the same color or using a premium paint-and-primer combo. Always apply 2 coats when covering dark colors, painting new drywall, or making a dramatic color change. Some deep reds, yellows, and oranges may need 3 coats.
How do I calculate paint for textured walls?
Textured walls have more surface area than their flat dimensions suggest. Reduce your expected coverage rate: use 250–300 sq ft per gallon for knockdown or orange peel textures, and 200–250 sq ft for heavy skip-trowel or popcorn surfaces. This calculator lets you select your wall texture so it adjusts coverage automatically.
Should I paint the ceiling — and how much paint does that take?
Yes — painting the ceiling refreshes the entire room. Ceiling area equals length × width (e.g., 12 × 14 = 168 sq ft). One gallon of flat ceiling paint covers 350–400 sq ft, so most single rooms need 1 gallon for 2 coats. Use a flat or matte finish to hide imperfections and reduce glare.
How much extra paint should I buy for waste and touch-ups?
Add 10–15% overage to your calculated amount. This accounts for roller absorption, tray waste, and cut-in overlap. Keep leftover paint sealed for future touch-ups — small scuffs and nail holes are inevitable. Label the can with the room and date so you can find it later.
How do I estimate paint for trim, doors, and windows?
A standard interior door takes about 0.5 gallons for 2 coats (both sides). Window trim averages 0.25 gallons per window. Baseboard and crown molding runs about 1 gallon per 200 linear feet of trim (2 coats). Use semi-gloss or satin finish for all trim — it is more durable and easier to clean than flat paint.
How much does it cost to paint a room yourself vs. hiring a pro?
DIY painting a 12×12 bedroom costs roughly $100–$200 in materials (2 gallons of mid-grade paint, tape, rollers, drop cloth). Hiring a professional painter costs $300–$600 for the same room including labor and materials. Pros are faster (4–6 hours vs. a full weekend) and the finish quality is noticeably better, especially on trim work and cut lines.
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