Paint Coverage Calculator

Wall Height (ft)

Total Wall Width (ft)

Number of Doors

Number of Windows

Number of Coats

Coverage (sq ft per gallon)

Price per Gallon ($)

How to Use the Paint Coverage Calculator

Planning a home renovation requires precision to avoid multiple trips to the hardware store or wasting money on excess supplies. Our Paint Coverage Calculator helps you determine exactly how many gallons of paint you need based on your room's specific dimensions.

Step-by-Step Instructions

Wall Dimensions: Measure the height of your walls from floor to ceiling and the total horizontal width of all walls you intend to paint.
Subtract Openings: Enter the number of doors and windows. The calculator automatically subtracts standard sizes (21 sq ft for doors, 15 sq ft for windows) from the total area.
Select Coats: Most professional finishes require at least two coats for full opacity and durability.
Coverage Rate: Standard interior paint typically covers 350-400 square feet per gallon. Check your paint can for the specific manufacturer's rating.

The Paint Calculation Formula

The math behind the calculator is straightforward but essential for accuracy:

            Total Area = ((Wall Height × Wall Width) - (Doors × 21) - (Windows × 15)) × Number of Coats
            
            Gallons Needed = Total Area / Coverage Rate

Realistic Example

Imagine you are painting a standard bedroom:

Walls: 8ft high and 50ft total width (400 sq ft total).
Openings: 1 door and 2 windows (subtracts 51 sq ft).
Net Area: 349 sq ft.
Two Coats: 698 sq ft total coverage needed.
Result: At 350 sq ft/gallon, you would need exactly 2 gallons of paint.

Pro Tips for Accurate Estimating

1. Texture Matters: Rough surfaces like stucco or brick can require up to 20% more paint than smooth drywall.

2. Primer: If you are painting a light color over a dark color, or painting new drywall, factor in a separate calculation for primer.

3. Buy Extra: It is always wise to have a small amount left over for future touch-ups. Rounding up to the nearest whole gallon is usually the safest bet.