¡Qué alivio!

Because this qué is being used in an exclamation.

In Spanish, qué takes an accent mark when it is:

• interrogative: ¿Qué quieres?
• exclamative: ¡Qué alivio!

By contrast, que without an accent is used in other roles, such as that, which, or because of the structure of the sentence:

• Creo que sí.
• El libro que compré...

So in ¡Qué alivio!, the accent marks it as exclamative qué.

Standard Spanish uses both an opening and a closing exclamation mark:

• ¡ ... !

So:

• ¡Qué alivio!

The opening mark tells you from the start that the sentence is exclamatory. This is normal and expected in correct written Spanish.

In informal texting, some people may omit the opening mark, but in proper writing you should include both.

Yes. In Spanish, short exclamations like this are completely natural and very common.

Examples:

• ¡Qué suerte!
• ¡Qué horror!
• ¡Qué alegría!
• ¡Qué alivio!

They work as standalone exclamations without needing a verb. English does this too in a similar way:

• What a relief!

So although there is no explicit verb, it is still a complete and natural utterance.

Because after exclamative qué, Spanish normally does not use the indefinite article in this kind of expression.

So you say:

• ¡Qué alivio!
• ¡Qué suerte!
• ¡Qué pena!

Not:

• ¡Qué un alivio! ❌

This is just the normal Spanish pattern with many exclamations. If you want a sentence with an article, you would structure it differently:

• Es un alivio.
• Fue un alivio enorme.

But as an exclamation, ¡Qué alivio! is the idiomatic form.

A good Spain Spanish pronunciation is approximately:

• keh ah-LEE-byoh

More precisely:

• qué → stress on the only syllable
• alivio → stress on li: a-LI-vio

IPA:

• [ke aˈliβjo]

A couple of useful notes:

• The v in Spanish is not pronounced like the English v. In most accents, b and v sound the same or very similar.
• vio here forms one syllable, so alivio has three syllables: a-li-vio.

People say it when something stressful, worrying, or uncomfortable is over.

Typical situations:

• You thought you had lost your phone, then you find it: ¡Qué alivio!
• You were waiting for exam results and they were better than expected: ¡Qué alivio!
• Someone arrives safely after a delay: ¡Qué alivio!

It sounds very natural in both spoken and written Spanish and is common in everyday conversation.

It is neutral and very widely usable.

You can say ¡Qué alivio!:

• in casual conversation
• at work
• in messages
• in many polite everyday situations

It is not slang, and it is not especially formal either. It’s just a normal, standard expression.

Yes, it can, depending on tone of voice or context.

For example, if someone finally does something very late, a person might say:

• ¡Qué alivio!

In that case, it could mean something like:

• Well, that took long enough
• Finally

But the basic, default meaning is sincere relief. Sarcasm comes from delivery, not from the phrase itself.

Yes, but the feeling is slightly different.

• ¡Qué alivio! = a direct exclamation, more emotional and immediate
• Es un alivio. = a statement, calmer and more descriptive

Compare:

• ¡Qué alivio! Ya está todo solucionado.
• Es un alivio saber que todo está bien.

So both are correct, but ¡Qué alivio! is the one you use for the spontaneous reaction.

Yes. Some common ones are:

• ¡Menos mal! → very common in Spain; often means thank goodness
• ¡Qué descanso! → more like what a relief / what a rest, depending on context
• ¡Por fin! → finally!

They are similar in some situations, but not identical:

• ¡Qué alivio! focuses on the feeling of relief.
• ¡Menos mal! often emphasizes that something bad was avoided.
• ¡Por fin! emphasizes that something finally happened after waiting.

So ¡Qué alivio! is a very useful and natural phrase, but it is not the only one Spaniards use.