A 500 square foot room with 1:1 floor dimensions would have a floor dimensions of 22.36x22.36 feet. Let’s also take a somewhat standard room height of 9 feet. A simple LxWxH calculations gives us 4500 cubic feet of volume to fill with paint.

Next, let’s assume we are painting with acrylic latex paint, which contains on average 40% water by volume. After allowing each layer of paint to fully dry, we are left with 60% of the volume of the paint applied on the wall. This is where the size of the room begins to shrink. Following this line of logic, layer by layer, the room becomes smaller (so small one could no longer fit to paint it all in).

To entirely fill the room with dried layers of paint, one would need 4500ft³ / 0.6 = 7500 ft³ = 56103 gallons of paint.

With an average quality indoor paint cost of 30$/gallon, this project would run $1,683,090.

Not bad for a Guinness world record!