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Paint Calculator

📅Last updated: October 10, 2025
✓Reviewed by: LumoCalculator Team

Calculate how many gallons of paint you need by room length, width and height. Include doors, windows and number of coats, then enter coverage per gallon and paint price to see total cost and paintable area. Works in feet or meters.

Calculate Paint Requirements

Paint Requirements

Paint Needed

2 gal

Total Cost

$103.5

Paintable Area

345 sq ft

Wall Area

396 sq ft

Cost Breakdown

Paint Cost:$90
Supplies (brushes, rollers, etc.):$13.5
Total Cost:$103.5

💡 Recommendation

Perfect size for a DIY project. Take your time for best results.

🎨 Paint Coverage Guide

Coverage by Paint Type

Premium Paint

400-450 sq ft per gallon

Standard Paint

350-400 sq ft per gallon

Budget Paint

250-350 sq ft per gallon

Primer

300-400 sq ft per gallon

Surface Adjustments

Smooth Walls

Use standard coverage

Textured Walls

Add 10-15% extra paint

Rough/Stucco

Add 20-25% extra paint

New Drywall

Prime first, then paint

🏠 Room Painting Tips

Preparation Steps

  • • Clean walls thoroughly and fill any holes
  • • Remove outlet covers and switch plates
  • • Apply painter's tape to trim and edges
  • • Lay drop cloths to protect floors
  • • Prime new or dramatically different colors

Painting Technique

  • • Start with ceiling, then walls, then trim
  • • Use "cutting in" technique for edges
  • • Apply paint in thin, even coats
  • • Maintain a wet edge to avoid lap marks
  • • Allow proper drying time between coats

Professional Tips

  • • Buy all paint at once to ensure color consistency
  • • Keep wet rags handy for immediate cleanup
  • • Remove tape while paint is still slightly wet
  • • Save some paint for future touch-ups
  • • Take before/after photos for your records

🖌️ Paint Types and Finishes

Paint Types

Latex/Water-Based

Easy cleanup, low odor, quick drying

Oil-Based

Durable, smooth finish, longer drying

Primer

Seals surface, improves adhesion

Paint Finishes

Flat/Matte

Hides imperfections, low sheen

Eggshell/Satin

Subtle sheen, easy to clean

Semi-Gloss

Durable, moisture resistant

Gloss

Highest durability, easiest to clean

💰 Cost Estimation Guide

Budget Range

$25-40

per gallon

Mid-Range

$40-60

per gallon

Premium

$60-100+

per gallon

Additional Costs to Consider

  • • Primer: $25-45 per gallon
  • • Brushes and rollers: $20-50
  • • Painter's tape: $5-15
  • • Drop cloths: $10-30
  • • Sandpaper and cleaning supplies: $10-20

⚠️ Common Painting Mistakes

Skipping Primer

Always prime new surfaces or dramatic color changes

Buying Cheap Paint

Quality paint covers better and lasts longer

Poor Preparation

Clean walls and fill holes before painting

Wrong Brush/Roller

Use appropriate tools for your paint type

Rushing the Job

Allow proper drying time between coats

Not Buying Enough

Always buy 10-15% extra for touch-ups

Frequently Asked Questions

How do I calculate how much paint I need?
Measure the length, width, and height of your room. Calculate wall area, subtract door and window areas, then divide by paint coverage (usually 350-400 sq ft per gallon). Our calculator does this automatically and accounts for multiple coats.
How much does a gallon of paint typically cover?
A gallon of quality paint typically covers 350-400 square feet with one coat. However, coverage can vary based on paint quality, surface texture, and application method. Primer may have different coverage rates.
Should I buy extra paint beyond the calculated amount?
Yes, always buy 10-15% extra paint for touch-ups, future repairs, and to account for waste during application. It's better to have slightly more than to run out mid-project and risk color matching issues.
How do I account for textured walls or ceilings?
Textured surfaces require 10-25% more paint than smooth surfaces. If painting textured walls or popcorn ceilings, increase your paint estimate accordingly. Our calculator includes a buffer for normal texture.
What about primer - do I need it?
Primer is recommended when changing colors dramatically, painting over dark colors, or painting new/bare surfaces. Primer typically has similar coverage to paint (350-400 sq ft per gallon) and requires the same calculation process.

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