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Paint Calculator

Never buy too much or too little

Units

Gallons Needed

2

Wall Area

352 sq ft

Coats

2

Coverage

604 sq ft

1
2

You Need

2

gallons

(Exactly 1.8 gal or 7 quarts)

Coverage Details

Total Wall Area352 sq ft
Paintable Area302 sq ft
With 2 Coats604 sq ft

Coverage Breakdown

Total Wall Area352 sq ft
Paintable Area302 sq ft
Total w/ 2 Coats604 sq ft

Paint Efficiency

Paintable vs Total Wall Area86%

14% of wall area excluded (doors & windows)

Tip: Add 10% extra for touch-ups and mistakes. Store leftover paint for future repairs.

Frequently Asked Questions

Q

How much paint do I need for a room?

Calculate wall area: (Room perimeter × Height) - doors & windows. Divide by 350-400 sq ft (coverage per gallon). Multiply by coats needed. Example: 12×12 room with 8ft ceilings = 384 sq ft walls ÷ 400 = 1 gallon per coat.

  • Wall area: Perimeter × Ceiling height
  • Subtract: 20 sq ft per door, 15 sq ft per window
  • One gallon = 350-400 sq ft per coat
  • Most rooms need 2 coats = double your estimate
  • Round UP and buy extra quart for touch-ups
Room SizeWall Area (8ft ceilings)1 Coat2 Coats
10×10 room320 sq ft1 gallon2 gallons
12×12 room384 sq ft1 gallon2 gallons
15×15 room480 sq ft1.5 gallons3 gallons
20×15 room560 sq ft1.5 gallons3 gallons
Q

How many coats of paint do I need?

2 coats is standard for most projects. Use 1 coat only for touch-ups or same-color refresh. Use 3+ coats when covering dark with light colors. Primer + 2 coats when painting new drywall or dramatic color changes.

  • 2 coats: Standard for best coverage and durability
  • Quality paint: Covers better, needs fewer coats
  • Dark to light: Use tinted primer to reduce coats
  • New drywall: MUST prime first
  • Primer: Different from paint, seals surface
SituationCoats NeededNotes
Same color refresh1 coatLight touch-up only
Similar color change2 coatsStandard recommendation
Light over darkPrimer + 2 coatsGray primer blocks dark
New drywallPrimer + 2 coatsSeals porous surface
High-quality paint1-2 coatsBetter coverage per coat
Q

What is paint coverage per gallon?

Standard coverage: 350-400 sq ft per gallon. Textured walls: 200-300 sq ft. Unfinished drywall: 200-250 sq ft. Smooth primed surface: 400-450 sq ft. Coverage varies by paint quality, color, and surface.

  • Premium paint: Often better coverage (worth the cost)
  • Dark colors: May cover less than label claims
  • Roller: More efficient coverage than brush
  • Spray: Uses 20-30% more paint
Surface TypeCoverage per GallonNotes
Smooth, primed400-450 sq ftBest coverage
Previously painted350-400 sq ftStandard
New drywall200-300 sq ftVery absorbent
Textured walls200-300 sq ftPeaks use more paint
Brick/stucco100-200 sq ftVery porous
Q

How do I calculate paint for ceilings?

Ceiling area = Length × Width. Same coverage rules apply (350-400 sq ft/gallon). Ceilings usually need 2 coats. Ceiling paint is flatter (hides imperfections) and thicker (less dripping).

  • Formula: Room length × Room width = ceiling sq ft
  • Coverage: Same 350-400 sq ft per gallon
  • Use ceiling-specific paint (flatter finish, less drip)
  • Typically 2 coats for best coverage
  • Popcorn ceiling: 50% less coverage (texture)
Room SizeCeiling Area1 Coat2 Coats
10×10100 sq ft1 quart2 quarts
12×12144 sq ft1 quart2 quarts
15×15225 sq ft1 gallon2 gallons
20×15300 sq ft1 gallon2 gallons
Q

What sheen should I use?

Flat/matte: Ceilings, low-traffic areas (hides imperfections). Eggshell: Living rooms, bedrooms. Satin: Kitchens, bathrooms, high-traffic. Semi-gloss: Trim, doors, cabinets. Gloss: Furniture, accents.

  • Higher sheen = more durable, more washable
  • Higher sheen = shows more imperfections
  • Kids rooms/hallways: Satin or semi-gloss
  • Match existing sheen if touching up
SheenDurabilityWashableBest For
Flat/MatteLowNoCeilings, formal rooms
EggshellMediumSomewhatLiving rooms, bedrooms
SatinMedium-HighYesKitchens, baths, kids rooms
Semi-GlossHighVeryTrim, doors, cabinets
GlossHighestVeryAccents, furniture
Q

How much does it cost to paint a room?

DIY: $100-300 (paint + supplies). Professional: $300-800 for average bedroom. Factors: Room size, ceiling height, paint quality, wall condition. Quality paint ($40-60/gallon) is worth it for durability.

  • Quality paint lasts 5-10 years vs 2-3 for cheap
  • Benjamin Moore, Sherwin Williams: Worth the premium
  • DIY time: 6-10 hours for average room (with prep)
  • Pro painters: Much faster, better at cutting in
ComponentDIY CostPro CostNotes
Paint (2 gal premium)$80-120IncludedWalls only
Primer (if needed)$25-40IncludedPer gallon
Supplies$30-50IncludedBrushes, rollers, tape
Labor$0 (your time)$200-500Per room
Total (avg bedroom)$100-200$350-700-

Example Calculations

1Standard Bedroom (12 × 10 ft)

Inputs

Room Length12 ft
Room Width10 ft
Ceiling Height8 ft
Doors1
Windows2
Coats2

Result

Paint Needed2 gallons
Wall Area352 sq ft
Paintable Area302 sq ft
Total Coverage (2 coats)604 sq ft
Exact Amount1.8 gal (7 quarts)

Wall area = 2 × (12 + 10) × 8 = 352 sq ft. Subtract 1 door (20 sq ft) and 2 windows (30 sq ft) = 302 sq ft paintable. With 2 coats: 604 sq ft / 350 sq ft per gallon = 1.73 gallons, rounded up to 2 gallons.

2Large Living Room (15 × 12 ft)

Inputs

Room Length15 ft
Room Width12 ft
Ceiling Height9 ft
Doors2
Windows3
Coats2

Result

Paint Needed3 gallons
Wall Area486 sq ft
Paintable Area401 sq ft
Total Coverage (2 coats)802 sq ft
Exact Amount2.3 gal (10 quarts)

Wall area = 2 × (15 + 12) × 9 = 486 sq ft. Subtract 2 doors (40 sq ft) and 3 windows (45 sq ft) = 401 sq ft paintable. With 2 coats: 802 sq ft / 350 sq ft per gallon = 2.29 gallons, rounded up to 3 gallons.

Formulas Used

Wall Area

Wall Area = 2 × (Length + Width) × Height

Calculates total wall surface area from room perimeter and ceiling height.

Where:

Length= Room length in feet
Width= Room width in feet
Height= Ceiling height in feet

Paintable Area

Paintable Area = Wall Area - (Doors × 20) - (Windows × 15)

Subtracts standard opening sizes (20 sq ft per door, 15 sq ft per window) from total wall area.

Where:

Doors= Number of doors (20 sq ft each)
Windows= Number of windows (15 sq ft each)

Gallons Needed

Gallons = (Paintable Area × Coats) / 350

Divides total coverage area by 350 sq ft per gallon average coverage.

Where:

Coats= Number of coats of paint
350= Average sq ft coverage per gallon

Paint Calculator Guide

Proper coverage calculation saves money and reduces waste. Always buy slightly more than calculated - matching colors later is difficult.

Paint quality matters. Premium paints ($40-60/gallon) cover better, last longer, and are easier to apply. The cost difference is minimal compared to labor and effort.

Preparation is key to a great paint job. Properly cleaned, patched, and primed walls make the paint go on smoothly and last years longer.

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Last Updated: Mar 9, 2026

This calculator is provided for informational and educational purposes only. Results are estimates and should not be considered professional financial, medical, legal, or other advice. Always consult a qualified professional before making important decisions. UseCalcPro is not responsible for any actions taken based on calculator results.

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