//
Estimate total square footage and gallons of paint required to coat room walls, ceilings, and renovation spaces.
💡 Buying Advice: If your project requires 1.83 gallons, purchasing 2 gallon cans ensures you have sufficient leftover paint for edge touch-ups and roller nap absorption.
Wall area is calculated by multiplying total perimeter length by the room's ceiling height:
For example, a 10 ft × 10 ft room has a perimeter of 40 ft (10 + 10 + 10 + 10). With an 8 ft ceiling: 40 × 8 = 320 sq ft.
A single coat rarely provides complete opacity and color fidelity. Multiplying wall area by coats gives the total painted surface:
320 sq ft × 2 coats = 640 sq ft total coverage.
One standard US gallon covers approximately 350 to 400 square feet of smooth wall:
640 sq ft ÷ 350 = 1.83 gallons $\rightarrow$ Buy 2 gallon cans.
To avoid over-purchasing paint on rooms with large openings, standard architectural deductions are:
Room Paint & Wall Coverage Calculator. Calculate total paint gallons, liters, and required coats based on room square footage, doors, windows, and primer requirements. ZechKit provides this tool completely free and online, optimized for instant, accurate computations directly inside your web browser.
A Paint Calculator determines the exact volume of paint and primer needed for interior and exterior painting projects.
Formulas: Gross Wall Area = 2 × (Length + Width) × Height. Net Paintable Area = Gross Wall Area − Windows Area − Doors Area. Gallons Required = (Net Area × Number of Coats) / Paint Coverage Rate (typically 350 to 400 sq ft per gallon).
Surface Porosity Impact: Unpainted new drywall, masonry, and textured stucco absorb more paint and require a dedicated primer coat plus 15%–20% extra paint.
Sheen & Trim Planning: Order separate specialized formulas for ceilings (flat/matte to hide imperfections) and high-touch trim/doors (semi-gloss or satin for scrubbability).
