How paint coverage affects the amount you need
Paint coverage is the bridge between surface area and purchase quantity. Once PrepMyBuild calculates the net wall area and applies the number of coats, it divides by the coverage rate to estimate paint volume.
Coverage is product-specific
A single universal coverage figure does not apply to every paint and surface. Use the manufacturer’s stated coverage as the best starting point, then allow for surface texture, application method and color change.
One coat versus two coats
Coverage ratings describe area per unit of paint, but every additional coat adds another full pass over the paintable area. That is why coat count has a direct impact on quantity.
Round to containers only after calculating volume
PrepMyBuild keeps the exact paint volume visible. Imperial mode also gives a whole-gallon purchase estimate; metric mode leaves the volume in litres so you can round to the can sizes sold locally.
After subtracting the entered openings, the calculator divides the net wall area by 350 sq ft/gal for one coat. Changing coverage to 300 immediately shows the extra paint required.