Spray paint can calculator
Spray paint coverage is measured in square feet per can, not gallons. Standard rules: a 4.5 oz can covers ~7 sq ft per coat, 12 oz covers ~20 sq ft, and 16 oz covers ~30 sq ft. Two coats are typical for spray applications because the film is thinner.
When spray paint is the right choice
Aerosol spray paint excels at: small metal items (patio furniture chairs, tools, bike frames), intricate ironwork (railings, gates), small wood projects, and detail work that would be tedious by brush. It's not the right product for walls, floors, large furniture, or anything bigger than ~50 sq ft — buy a quart and a brush instead.
Coverage drops on textured or rusty surfaces
The square-foot numbers assume smooth, primed metal. On rusty wrought iron, raw wood, or textured plastic, plan for 30–50% more cans. The aerosol film is thinner than brushed paint, so it doesn't fill texture the same way.
FAQ
A typical metal patio chair has ~10 sq ft of paintable surface. Two coats = 20 sq ft. One 12 oz can does it with extra for touch-up. A wood Adirondack chair has more surface (~25 sq ft) — plan for two cans.
A bike frame is ~6–8 sq ft of paintable surface. One 12 oz can with two coats handles a frame and a fork easily, with leftover for touch-up.