How many square feet does a gallon of paint cover?

One gallon of quality interior paint typically covers 350-400 square feet on smooth, primed surfaces. Coverage decreases to 250-300 square feet on textured walls, porous surfaces, or when covering dark colors with light paint.

Do I need one or two coats of paint?

Two coats are recommended for best results, especially when changing colors dramatically, painting over repairs, or using low-sheen finishes. One coat may suffice when repainting the same color with quality paint on smooth, previously painted surfaces.

How do I calculate paint needed for a ceiling?

Multiply length by width to get square footage. A 12x14 foot ceiling equals 168 square feet. Divide by 350 (coverage per gallon) to get gallons needed. For this ceiling, 0.48 gallons for one coat, so buy 1 gallon for two coats.

What is the difference between flat, eggshell, and semi-gloss paint?

Flat paint hides imperfections but is hard to clean - good for ceilings and low-traffic areas. Eggshell has slight sheen and is washable - ideal for living rooms and bedrooms. Semi-gloss is durable and moisture-resistant - best for kitchens, bathrooms, and trim.

How long should I wait between coats of paint?

Latex paint typically needs 2-4 hours between coats in normal conditions (50-85 degrees F, moderate humidity). Oil-based paint requires 24 hours. Always check the can for specific recommendations, and wait longer in cold or humid conditions.

Do I need to use primer before painting?

Primer is recommended for new drywall, bare wood, stains, dramatic color changes (dark to light), or glossy surfaces. Many quality paints include primer, but separate primer provides better adhesion and coverage for challenging surfaces.

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Paint Calculator

Calculate gallons for walls, ceilings, trim, and exteriors

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Last verified: February 2026Accuracy tested

Calculated in your browser — we never store your dataIncludes standard waste factors

Room Length (ft)

Room Width (ft)

Wall Height (ft)

Number of Coats

Price per Gallon ($)

● National avg · updated Feb 20

Calculation Result

3 gallons needed

826 sq ft coverage

~15% deducted for doors/windows

Estimated cost: $105–$165

Sources & Methodology

Formula: Gallons = Total Area / 350 sq ft per gallon

Coverage rate varies by paint type and surface

Source: Paint manufacturer coverage guidelines

Standard coverage: 350-400 sq ft/gallon. Textured surfaces need more.

View full methodology & accuracy testing

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How to Use the Paint Calculator

Our paint calculator estimates how many gallons of paint you need based on your room dimensions and number of coats. We automatically deduct 15% for doors and windows to give you a realistic estimate. Need to measure your walls? Use our square footage calculator first.

Coverage Assumptions

We assume standard coverage of 350 square feet per gallon, which is typical for quality interior latex paint on primed surfaces. Textured walls, dark colors covering light, or unprimed surfaces may require more paint.

Tips for Better Results

Two coats are recommended for best coverage and durability
Always buy slightly more than calculated to ensure color consistency
For ceilings, calculate separately using length × width
Primer may be needed for new drywall, stains, or dramatic color changes

Related Room Renovation Projects

Planning a full room renovation? You may also need our tile and flooring calculator for new floors, drywall calculator for wall repairs, or lumber calculator for trim and molding. Calculate your project percentage complete to track progress.

Professional Considerations

For high ceilings, intricate trim work, or special finishes like faux painting, consider consulting a professional painter for accurate time and material estimates.

Frequently Asked Questions

A 12x12 room with 8-foot ceilings has about 384 square feet of wall space. After deducting 15% for doors and windows, you need approximately 326 square feet of coverage. One gallon covers 350-400 sq ft, so one gallon is sufficient for one coat, or two gallons for two coats.