The 'one gallon covers 400 square feet' paint claim is a bold-faced lie
I measured my 10x12 foot bedroom and bought a gallon based on the can. Ran out halfway through the second coat. The math just doesn't add up unless you're painting over bare, perfectly smooth drywall, which nobody is. Anyone else have a real-world coverage number they actually trust?
Honestly, that "perfect surface" idea is why I use the numbers as a guide, not a rule. Tbh they still get me in the right ballpark for how much to buy.