Paint Quantity Calculator
Based on standard coverage of 350 sq ft/gallon
Planning a room makeover? Nothing kills the DIY vibe faster than running out of paint mid-wall—or realizing you’ve bought three gallons too many.
Our Paint Quantity Calculator takes the math out of the equation.
Whether you are refreshing a cozy bedroom or tackling a large living area, this tool estimates the precise amount of paint required so you can shop with confidence and stay on budget.
How to Use This Paint Quantity Calculator
- Choose Your Units: Start by selecting your preferred system at the top: Imperial (Feet & Gallons) or Metric (Meters & Liters). The calculator will automatically convert the math for you.
- Enter Room Dimensions: Input the Length, Width, and Ceiling Height of your room. You can type the exact number or use the + and – buttons to quickly adjust the size.
- Account for Openings: Don’t pay to paint the glass! Enter the number of Windows and Doors in the room. We subtract these standard areas (approx. 15 sq. ft. for windows and 21 sq. ft. for doors) from your total.
- Select Number of Coats: Use the slider to indicate how many layers you intend to apply.
- Recommendation: We default to 2 coats, which is standard for most color changes to ensure an even, rich finish.
Important Notes & Limitations
While this calculator provides a highly accurate estimate, keep these factors in mind before heading to the hardware store:
- Standard Coverage: This tool assumes a standard spread rate of 350 square feet per gallon (approx. 9 square meters per liter). Check your specific paint can label, as high-quality primers or specialty paints may vary.
- Texture Matters: Rough or textured walls (like stucco, brick, or popcorn textures) absorb significantly more paint. If your walls aren’t smooth, consider buying 10–20% extra to be safe.
- Color Changes: If you are painting a light color over a dark wall (or vice versa), you may need an additional coat or a separate primer layer that this calculator does not include.
💡 Pro Tip: The “Boxing” Technique
If the calculator determines you need multiple gallons of paint, don’t just open one can at a time!
Use the “Boxing” method – Pour all your individual gallons into a large 5-gallon bucket and mix them together before you start painting. This ensures the color remains perfectly consistent across the entire room, eliminating slight shade variations that can sometimes occur between different cans.
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