Paint, Flooring & Wall Materials

Paint Calculator

Estimate paint cans and primer needed for walls and ceilings with door and window deductions and configurable coat coverage.

Wall Measurements

Enter wall dimensions and openings

Total Wall Width / Perimeter (ft)Sum of all walls to paint

Wall Height (ft)

Doors Count (-21 sq ft ea)

Windows Count (-15 sq ft ea)

Number of Coats

Coverage per Unit (sq ft/gal)

Paint Container Size

Include Ceiling Painting

Estimated Paint Required

Rounded up for full containers

Containers to Purchase

3 1-Gallon Cans

Actual estimated paint volume: 2.18 gallons

Gross Wall Area:432 sq ft

Deductions (Doors/Windows):−51 sq ft

Net Paintable Wall Area:381 sq ft

Total Coverage Area (2 coats):762 sq ft

Primer Recommendation: For raw unpainted drywall or high-contrast color transitions, purchase ~2 gallons of dedicated primer sealer for a primer coat.

How It Works & Calculation Formula

Formula Summary: Paint Cans = ceil((Net Wall Area × Coats) ÷ Coverage per Can).

Step-by-Step Calculation:

Calculate gross wall area: Total Wall Width × Wall Height.
Calculate openings: (Doors × 21 sq ft) + (Windows × 15 sq ft).
Net Wall Area = Gross Wall Area − Openings.
Add ceiling area if selected: Room Length × Room Width.
Total Coat Area = Net Area × Number of Coats (typically 2).
Volume Needed = Total Coat Area ÷ Coverage per gallon/liter (standard 350 sq ft/gal or 10 sq m/L).
Round up to the nearest whole can.

Worked Example Calculation

Sample Inputs:

Total Wall Width:48 ft (12×12 room)
Wall Height:9 ft
Doors:1
Windows:2
Coats:2

Expected Output:

Net paintable area: 381 sq ft. Total coat area: 762 sq ft. Paint required: 2.18 gallons (Purchase 3 one-gallon cans).

Practical Tips & Trade Guidelines

Standard drywall absorbs more paint on the first coat. Always apply primer to new plaster or drywall patches.
Dark-to-light color transitions often require 3 coats or a high-hide tinted primer.
Keep one leftover quart of mixed paint tightly sealed for future scuff touch-ups.
Quality paint with high solids content covers better and lasts years longer than bargain formulations.

Frequently Asked Questions

One standard US gallon of quality paint covers approximately 350 to 400 square feet (32 to 37 square meters) with one coat on a primed, smooth surface.

Important Renovation Notice

Calculations are mathematical estimates based on standard trade conventions. Always field-verify room measurements, examine packaging labels, and check with a licensed contractor before purchasing materials or starting installation.