Ter um mau dia.

You use this when you want to express a generally negative experience over a period of time, usually a day. It’s a flexible phrase. You can say it to a friend, a colleague, or even just think it to yourself. It’s a simple way to communicate your mood. It’s often used as a response when someone asks how you are.

Imagine you wake up late. Then, your car won't start. At work, your boss is upset. You spill coffee on your shirt. You might text a friend: "Hoje estou tendo um mau dia." (Today I'm having a bad day.) Or maybe you see a friend looking glum. You ask, "Tudo bem?" They might reply, "Não muito, estou tendo um mau dia." (Not really, I'm having a bad day.) It’s a very common expression.

Use Ter um mau dia when you've experienced a series of unfortunate events. It's perfect for when you feel overwhelmed or just down. It fits when your plans get ruined. Think of a day where nothing goes right from start to finish. It's also good for acknowledging someone else's bad day. "Sinto muito que você esteja tendo um mau dia." (I'm sorry you're having a bad day.)

Don't use this for minor annoyances. If you just missed your bus by two seconds, it’s probably not a mau dia. Maybe just a chatinho (annoying) moment. Avoid it if you're trying to be overly positive in a professional setting. It can sound a bit whiny if used inappropriately. Also, avoid it if you actually had a *good* day! That would be confusing.

Learners sometimes try to be too literal. They might say Fazer um mau dia (to make a bad day). That sounds like you're actively creating a bad day, which is weird! Or they might use Ser um mau dia (to be a bad day) when talking about their personal experience. This is more for describing the day itself, not your feeling about it.

There are other ways to express unhappiness. Estar de mau humor means to be in a bad mood. Ter um dia péssimo is stronger, meaning a terrible day. Dia ruim is a simpler version, just 'bad day'. Estar para baixo means to feel down or depressed. These all convey negative feelings but with slightly different nuances or intensity.

Often, people shorten it. Instead of Estou tendo um mau dia, they might just say Tive um mau dia (I had a bad day) if it's over. Or simply, Que dia ruim! (What a bad day!). Sometimes, context makes it clear, and people might just say Estou péssimo (I'm terrible) or Não estou bem (I'm not well). The core idea of a day gone wrong remains.