Buying a bit more paint than your exact calculation gives you insurance – for touch-ups and for small miscalculations. Walls absorb paint differently depending on texture, age and previous colour. You might end up using slightly more than the theoretical coverage suggests.
If you run out halfway through a wall, rushing to the store and trying to match another batch perfectly can be stressful. Even the same colour mixed twice can have tiny variations. Having a little extra from the original batch helps keep everything consistent.
Later, when walls get scuffed or scratched, that leftover paint is perfect for quick touch-ups without needing to repaint entire sections.
It’s easier to store a small, tightly sealed can than to struggle with mismatched colours or incomplete jobs.
