The HomeCraft Paint Calculator helps you estimate exactly how much paint you need — walls, ceiling, and trim. Accurate to the gallon.
Our free paint calculator takes the guesswork out of your next painting project. Simply enter your room's length, width, and wall height, then specify the number of doors and windows so we can accurately deduct those unpaintable areas. Choose how many coats you plan to apply — most interior paint jobs need two coats for even, professional coverage — and the calculator instantly shows you how many gallons (or liters) you need to buy.
The industry standard for paint coverage per gallon is approximately 350 square feet on a smooth surface, and around 300 square feet on textured or rough walls. Our calculator defaults to 350 sq ft/gallon but you can adjust this value based on your specific paint brand. Premium paints often cover more area per gallon, while budget paints and dark colors may require more product for full opacity.
Professional painters always deduct doors and windows from the total wall area before calculating paint. A standard interior door covers approximately 20 square feet, while a typical window takes up around 15 square feet. Our tool handles these deductions automatically, preventing you from over-purchasing paint and wasting money. Ceiling paint is calculated separately as its own product (typically a flat or matte finish), and trim paint for baseboards and molding uses a different formula based on linear feet of trim.
The bottom line: this room paint estimator gives you a professional-level material list in under 30 seconds, saving you multiple hardware store trips and ensuring you never run out of paint mid-project.
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