How much paint do I need?

Paint coverage formula: 1 gallon covers 350-400 sq ft (1 coat). Premium paint: 400 sq ft/gallon (better coverage). Budget paint: 300 sq ft/gallon (thinner, needs more). Calculation: Net wall area ÷ coverage ÷ coats = gallons. Example: 715 net sq ft ÷ 350 ÷ 2 coats = 4.1 → buy 5 gallons.

How many coats of paint do I need?

Coats needed: New drywall: 1 primer + 2 finish = 3 coats. Light color over dark: 2-3 coats. Dark color over light: 2 coats. Same color touch-up: 1 coat. Red/yellow/orange: 3 coats (transparent pigments).

What does professional painting cost?

Painting costs: DIY: $0.50-1/sq ft (paint only). Professional: $2-6/sq ft (labor + materials). Breakdown: Paint: $35-75/gallon. Labor: $1-3/sq ft. Supplies: $0.25-0.50/sq ft. Example (800 sq ft): DIY $400, Pro $2,400.

Why does the calculator subtract area for doors and windows?

Doors and windows don't get painted, so counting their area as wall space overstates how much paint you actually need. This calculator deducts about 20 sq ft per standard interior door and 15 sq ft per standard window from your entered wall area before calculating gallons - the same deduction industry-standard calculators (Sherwin-Williams, Behr) use. If your doors or windows are unusually large or small, adjust your entered wall area manually to compensate.

Construction Calculators

Paint Calculator

Calculate paint needed based on room dimensions and coverage rate with detailed project planning for interior and exterior painting. Features gallons and quarts required accounting for number of coats, cost estimation by paint quality (economy, premium, high-end), coverage adjustment for walls vs ceilings (350-400 sq ft/gallon), door and window deductions, primer calculations, and total project budget including supplies like brushes, rollers, tape, and drop cloths for accurate renovation planning.

How to Use the Paint Calculator

Use the Paint Calculator to paint needed based on room dimensions and coverage rate with detailed project planning for interior and exterior painting. Features gallons and quarts required accounting for number of coats, cost estimation by paint quality (economy, premium, high-end), coverage adjustment for walls vs ceilings (350-400 sq ft/gallon), door and window deductions, primer calculations, and total project budget including supplies like brushes, rollers, tape, and drop cloths for accurate renovation planning.. Enter your values to get accurate, instant results tailored to your situation.

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Calculate paint accurately and instantly
Calculate calculate accurately and instantly
Calculate paint accurately and instantly
Calculate needed accurately and instantly
Calculate construction accurately and instantly

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Paint Calculator Guide

Paint estimation

Expert Tips

One Gallon Covers 350-400 Sqft (One Coat): Standard coverage: 400 sqft per gallon. Porous surfaces (bare drywall, stucco): 250-300 sqft. Smooth surfaces (previously painted): 400-450 sqft. Always plan for 2 coats for even coverage. 1,500 sqft walls = 8-10 gallons total (2 coats).
Quality Paint Worth 20-40% Premium: Budget paint: $20-30/gallon (needs 3 coats, poor coverage). Premium: $40-70/gallon (2 coats, better durability). Over 5 years: Budget = $60 + 3× labor, premium = $60 + 2× labor. Premium actually cheaper long-term. Brands: Sherwin-Williams, Benjamin Moore > Behr > cheap box store.
Wall Area Formula: (Length + Width) × 2 × Height: Room 15ft × 12ft, 9ft ceilings: (15 + 12) × 2 × 9 = 486 sqft. Subtract doors/windows: Standard door 20 sqft, window 15 sqft. 486 - 40 (2 doors) - 45 (3 windows) = 401 sqft. 401 ÷ 400 = ~1 gallon per coat.
Primer Essential for Bare Surfaces and Dark Colors: Skip primer on: Previously painted, same-color refresh. Use primer on: Bare drywall, stained/damaged walls, dramatic color change (dark to light or vice versa). Primer cost: $15-30/gallon. Saves 1 coat of expensive topcoat.

Essential Fundamentals — Coverage calculation

Paint Quantity

Surface Area Calculation: Walls: Add all wall lengths, multiply by height. Ceiling: Length × width. Trim: Linear feet × 0.5 ft average width. Subtract openings: Doors ~20 sqft, windows ~15 sqft. Divide total sqft by 350 (conservative coverage) = gallons per coat.
Number of Coats: Two coats standard for uniform finish. Dark to light: 2-3 coats. Light to dark: 2 coats usually sufficient. Bare drywall: Primer + 2 coats. Ceiling: 1-2 coats (less wear than walls). Calculate: Total sqft ÷ 350 × number of coats = total gallons needed.

Advanced Strategies — Professional results

Quality Techniques

Surface Preparation: Clean walls, patch holes, sand rough spots before painting. Poor prep shows through any paint. Prime stains, water damage, or color changes. Prep takes 50% of project time but determines final quality.
Application Methods: Roller for walls (fastest coverage). Brush for trim, edges, cutting in. Sprayer for large areas or textured surfaces (fastest but needs more skill). Quality tools matter—cheap brushes leave streaks.
Timing and Conditions: Paint when 50-85°F, low humidity. Avoid direct sunlight on wet paint. Allow proper drying between coats. Rushing coats causes peeling, uneven finish. Read paint can for specific dry times.

Frequently Asked Questions

How much paint do I need?: Paint coverage formula: 1 gallon covers 350-400 sq ft (1 coat). Premium paint: 400 sq ft/gallon (better coverage). Budget paint: 300 sq ft/gallon (thinner, needs more). Calculation: Net wall area ÷ coverage ÷ coats = gallons. Example: 715 net sq ft ÷ 350 ÷ 2 coats = 4.1 → buy 5 gallons.
How many coats of paint do I need?: Coats needed: New drywall: 1 primer + 2 finish = 3 coats. Light color over dark: 2-3 coats. Dark color over light: 2 coats. Same color touch-up: 1 coat. Red/yellow/orange: 3 coats (transparent pigments).
What does professional painting cost?: Painting costs: DIY: $0.50-1/sq ft (paint only). Professional: $2-6/sq ft (labor + materials). Breakdown: Paint: $35-75/gallon. Labor: $1-3/sq ft. Supplies: $0.25-0.50/sq ft. Example (800 sq ft): DIY $400, Pro $2,400.
Why does the calculator subtract area for doors and windows?: Doors and windows don't get painted, so counting their area as wall space overstates how much paint you actually need. This calculator deducts about 20 sq ft per standard interior door and 15 sq ft per standard window from your entered wall area before calculating gallons - the same deduction industry-standard calculators (Sherwin-Williams, Behr) use. If your doors or windows are unusually large or small, adjust your entered wall area manually to compensate.