Paint Coverage Calculator interactive tool
* Assumes standard coverage. Textured walls or bare drywall may require more paint or a primer coat. It is recommended to buy 10% extra.
What Is Paint Coverage?
A paint coverage calculator estimates how many gallons of paint a room or exterior surface may require. It uses your dimensions, openings, number of coats, and a coverage assumption to support a shopping estimate.
The Standard Paint Coverage Formula
Most high-quality interior acrylic paints follow a standard coverage rate:
- 1 Gallon covers roughly 350 to 400 square feet (for a single coat).
- 1 Quart covers roughly 100 square feet.
However, this is only a baseline. Porous surfaces (like fresh drywall or textured stucco) will soak up significantly more paint, reducing your coverage. Applying a high-quality primer first seals the surface, ensuring the paint spreads evenly and adheres to the manufacturer's stated coverage rates.
How Many Gallons for a 12x12 Room?
For a standard 12x12 foot room with 8-foot ceilings, and assuming two coats of paint, you would typically need between 2 to 3 gallons of paint. This estimate accounts for the walls; if painting the ceiling as well, add another gallon. Always consider subtracting the area of large windows and doors for a more precise calculation.
Why Accurate Paint Calculation Matters
Paint is expensive, and buying too much creates waste. Buying too little can also interrupt a project or lead to color differences between batches. By entering wall dimensions and subtracting doors and windows, this tool gives you a more useful starting estimate. Check the paint label for its coverage rate before purchasing.
How To Use the Paint Coverage Calculator
- Enter the length and height of the walls you plan to paint to calculate the total surface area.
- Add any unpainted areas (like windows and doors) to subtract them from the total.
- Select the number of coats you plan to apply (usually 2 for a professional finish).
- Review the estimated gallons required for your DIY painting project.
Gallons of paint for a room
This paint calculator estimates gallons from wall dimensions, doors, windows, coverage per gallon, and number of coats. Surface texture and product coverage can change the amount, so use the result as a purchasing estimate.
Need the formula or convention behind this result? Read the calculator methods and assumptions.