Paint Calculator

Calculate how many gallons of paint you need for any room. Accounts for doors, windows, number of coats, and primer. Multi-room support with cost estimates.

Room 1

Length (ft)

Width (ft)

Height (ft)

Doors

Windows

Paint Options

Number of Coats

Coverage (sqft/gallon)

Price per Gallon ($)

PrimerInclude primer

Gallons Needed

(1.7 exact)

Paintable Area

301.0 sqft

Total Cost

$95.00

Area Breakdown

Total Wall Area352.0 sqft

Doors (1 x 21 sqft) + Windows (2 x 15 sqft)-51.0 sqft

Paintable Area301.0 sqft

Paintable (86%)

Doors/Windows (14%)

Cost Breakdown

Paint: 2 gallons x $35.00$70.00

Primer: 1 gallon x $25.00$25.00

Total Material Cost$95.00

Paint Coverage Reference

Paint Type	Coverage	Notes
Interior Flat/Matte	350-400 sqft/gal	Best for ceilings, low-traffic areas
Interior Eggshell	350-400 sqft/gal	Good all-purpose, easy to clean
Interior Semi-Gloss	350-400 sqft/gal	Kitchens, bathrooms, trim
Exterior Latex	250-350 sqft/gal	Lower coverage on rough surfaces
Primer/Sealer	300-350 sqft/gal	First coat on new surfaces
Textured Paint	150-200 sqft/gal	Much thicker application

Painting Tips

Buy Extra

Always buy 10-15% extra for touch-ups and waste

Two Coats Recommended

Two coats provide better coverage, durability, and color depth

Primer First

Use primer on new drywall, dark colors, or stained surfaces

Surface Prep

Clean, sand, and patch walls before painting for best results

How to Use Paint Calculator

1Enter room dimensions
2Specify doors and windows
3Choose coats and coverage
4View gallons needed and cost

Frequently Asked Questions

How much paint do I need for a room?▾

A gallon of paint covers about 350-400 sqft. A typical 12x12 room with 8ft ceilings needs about 1.5 gallons for one coat or 3 gallons for two coats.

Do I need primer?▾

Use primer when painting over dark colors, new drywall, stains, or switching between paint types. Self-priming paints can skip this step for minor color changes.

How many coats of paint do I need?▾

Most colors need 2 coats for full coverage. Light over dark or dark over light may need 3 coats. Quality paints with high pigment may only need 1 coat.

About Paint Calculator

Calculate how many gallons of paint you need for any room. Accounts for doors, windows, number of coats, and primer. Multi-room support with cost estimates.

NexTool's Paint Calculator is completely free to use with no sign-up required. Your data is processed directly in your browser and never sent to our servers, ensuring complete privacy and instant results.