Online Paint Calculator
Use this calculator to estimate the amount of paint you'll need for your next project. Accurate measurements and understanding paint coverage are key to avoiding multiple trips to the store or wasting paint.
Typical coverage is 300-400 sq ft per gallon.
Sum of doors, windows, or other areas not to be painted.
Paint Estimate:
Understanding Your Paint Needs
Painting a room can dramatically change its look and feel, but estimating the right amount of paint is crucial for a smooth project. Our Online Paint Calculator simplifies this process by taking into account the key dimensions of your space and other important factors.
How the Calculator Works
The calculator uses standard geometric formulas to determine the total surface area of your walls and ceiling. It then subtracts any non-paintable areas (like doors and windows) to give you the net area to be painted. Finally, it divides this net area by the paint's coverage rate per gallon and multiplies by the number of coats you plan to apply.
- Room Length & Width: These define the floor and ceiling area, and contribute to the perimeter for wall calculations.
- Room Height: Essential for calculating the vertical surface area of the walls.
- Number of Paint Coats: Most projects require two coats for optimal color depth and durability, especially when changing colors significantly.
- Paint Coverage (sq ft per gallon): This is usually found on the paint can label. It indicates how many square feet a single gallon of that specific paint can cover. Factors like paint quality, sheen, and surface porosity can affect this number. A common range is 300-400 sq ft per gallon.
- Non-Paintable Area: Don't forget to account for doors, windows, built-in shelving, or other areas you won't be painting. Subtracting these areas ensures a more accurate estimate.
Tips for Accurate Measurement
- Measure Twice: Always double-check your measurements to avoid errors.
- Measure Each Wall: While a rectangular room is straightforward, L-shaped or irregularly shaped rooms require measuring each wall segment individually.
- Account for Ceiling: If you're painting the ceiling, ensure you include its area in your calculations.
- Consider Surface Texture: Rough or highly textured surfaces (like stucco or heavily textured drywall) may absorb more paint and require a lower coverage rate or an additional coat.
- Primer: If you're painting over a dark color with a light one, or painting new drywall, a primer might be necessary. Primer coverage rates can differ from paint.
Example Calculation
Let's say you have a room that is 12 feet long, 10 feet wide, and 8 feet high. You plan to apply 2 coats of paint, and your chosen paint covers 350 sq ft per gallon. There's a door and a window totaling 40 sq ft that you won't paint.
- Wall Area: 2 * (12 ft + 10 ft) * 8 ft = 2 * 22 ft * 8 ft = 352 sq ft
- Ceiling Area: 12 ft * 10 ft = 120 sq ft
- Total Surface Area: 352 sq ft (walls) + 120 sq ft (ceiling) = 472 sq ft
- Net Paintable Area: 472 sq ft – 40 sq ft (non-paintable) = 432 sq ft
- Paint Needed (1 coat): 432 sq ft / 350 sq ft/gallon = 1.23 gallons
- Total Paint Needed (2 coats): 1.23 gallons * 2 = 2.46 gallons
Based on this, you would likely need to purchase three 1-gallon cans of paint to complete the project, allowing for a small buffer.
Always round up your paint purchase to the nearest full can to ensure you have enough, as running out mid-project can be frustrating and lead to color inconsistencies if you have to buy a different batch.