Estimate how much paint you need for walls and ceilings. Supports multiple surfaces, door/window deductions, coats, and custom coverage rates.
BuildCostMate's free paint calculator helps you estimate how much paint you need for walls and ceilings before you shop. It supports multiple surfaces in one calculation, door/window area deductions, a configurable number of coats, and a fully editable coverage rate — since real paint coverage varies significantly between brands, finishes, and surface textures.
Note: Coverage rate is the single biggest factor in accuracy — it varies enormously by paint type (a thick, textured masonry paint covers far less area per liter than a thin interior emulsion), so always check your specific product rather than relying on a generic default.
It depends on the total wall area, the number of coats, and your paint's coverage rate. Our Paint Calculator multiplies your net paintable area by the number of coats, divides by your paint's coverage rate, and adds a wastage margin to give you a container count.
Coverage varies significantly by paint brand and surface texture. A common starting point is around 350-400 sq ft per gallon (about 10 m² per liter) per coat, but always check the figure printed on your specific paint can and adjust the calculator's default accordingly.
Two coats is standard for most interior walls, especially over a different existing color. A single coat may suffice for touch-ups or when using a high-opacity paint over a similar base color.
Yes, the Paint Calculator is completely free to use with no registration required.