Paint Coverage Calculator
Adjust the parameters below to compute materials and estimate project costs.
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Breakdown Details
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Guidelines & Field Recommendations
• Primer: Essential for new drywall or patching compound.
• Coats: 2 coats are standard for uniform color saturation.
Paint Finishes: Eggshell for walls, semi-gloss for trim.
Calculation Formulas & Steps
Wall Area = 2 × (Length + Width) × Height. Deductions = Openings × 20 sq ft. Paint Gallons = (Net Area ÷ 350 sq ft per gallon) × Coats.
Worked Example (Step-by-Step Math)
Find perimeter and multiply by ceiling height.
Perimeter = 2 × (14 + 12) = 52 ft. Area = 52 × 8 = 416 sq ftEach door/window averages 20 sq ft of non-painted space.
Deductions = 3 openings × 20 sq ft = 60 sq ft. Net Area = 356 sq ftOne gallon covers approx. 350 sq ft.
Gallons = (356 ÷ 350) × 2 coats ≈ 2.03 ≈ 2 GallonsPaint Coverage Rates
Estimated coverage based on paint volume.
| Project Condition | Reference Metric |
|---|---|
| 1 Gallon Can | Covers approx. 350 to 400 square feet |
| 1 Quart Can | Covers approx. 90 to 100 square feet |
Critical Mistakes to Avoid
- !Mistake 1: Painting on bare, porous drywall without priming first, causing the wall to absorb all the paint unevenly.
- !Mistake 2: Underestimating windows and doors sizing.
Frequently Asked Questions
How many gallons of paint do I need for a 12x12 room with two coats?
For a standard 12x12 foot room with 8-foot ceilings, you will need approximately two (2) gallons of wall paint to apply two coats. The net wall surface area (with 3 standard door/window openings deducted) is about 324 sq ft, and one gallon covers ~350 sq ft.
What is the average paint coverage per gallon on drywall?
A standard gallon of latex wall paint covers 350 to 400 square feet when applied to pre-primed drywall. However, if you are painting bare, unprimed drywall or heavily textured walls, the surface is porous and coverage drops to about 250 square feet per gallon.
How many coats of paint are required on new drywall?
New drywall requires three coats total: one coat of drywall primer (to seal the highly absorbent paper and joint compound) followed by two coats of premium latex wall paint for uniform color.
Does paint cover textured walls less than smooth drywall?
Yes. Heavily textured walls have up to 20% more surface area than flat walls. A gallon of paint that covers 350 sq ft on smooth walls will only cover 280-300 sq ft on textured walls.
How much paint do I need for a 12x12 foot ceiling?
A 12x12 foot ceiling is 144 sq ft. A single quart of ceiling paint covers about 90-100 sq ft, which is not enough. You must purchase a one-gallon can, which will leave you with about half a gallon of leftover paint.
Do I need a separate primer coat before painting?
Yes, if painting brand new drywall or making a dramatic color change. Primer seals the surface so the top coat adheres evenly.
What is the difference between flat, eggshell, and semi-gloss paint finishes?
Flat has no sheen and hides wall flaws but is hard to clean. Eggshell has a soft glow and is standard for living areas. Semi-gloss is durable and shiny, making it optimal for kitchens and baths.
Complete Tools Checklist
- Paint Roller & Frame
- Paint Brushes
- Paint Tray
- Painter's Tape
- Drop Cloths