How many days without food can kill a cat?

Generally a cat that eats and drinks nothing will die in about a week, depending on its constitution. Underage or weak cats may starve in 5 days, but even healthy cats can only last about a week.

So if the owner is away for long, board the cat with a friend or pet shop to prevent accidents. For a 3-4 day trip, make sure to leave plenty of food and water.