Learn Hardcore Portuguese (Portugal): Eu volto em meia hora.

In Portuguese (especially European), the present indicative often expresses a near-certain or scheduled future when there’s a time expression. Volto em meia hora = I’ll be back in half an hour. Alternatives:

Vou voltar em meia hora. (near future, very common)
Voltarei em meia hora. (simple future; tends to sound more formal or less immediate)

Is em meia hora the best way to say “in half an hour” in Portugal?

It’s understood and used, but many speakers prefer:

Daqui a meia hora (from now in half an hour; unambiguous in EP)
Dentro de meia hora (within/in half an hour; also common) So you’ll often hear Volto daqui a meia hora or Regresso dentro de meia hora.

Does em meia hora ever mean “within half an hour” or “it takes half an hour”?

Yes, em + time can be ambiguous:

Future point: Volto em meia hora. (I’ll be back in half an hour.)
Duration to complete: Faço isto em meia hora. (I do this in/it takes me half an hour.) If you want to avoid ambiguity about “from now,” use daqui a meia hora.

Why meia and not meio?

Agreement. Hora is feminine, so meia (feminine form of “half”) is required:

meia hora (half an hour)
meio minuto (half a minute; minuto is masculine)

Could I say trinta minutos instead?

Yes:

Volto em trinta minutos. But meia hora is more idiomatic in everyday speech.

Is voltar the right verb here? What about regressar or vir?

Voltar = to go/come back; very common and natural: Volto em meia hora.
Regressar = to return; a bit more formal/common in Portugal: Regresso daqui a meia hora.
Vir (to come) is from the listener’s point of view. Venho em meia hora is possible if you mean “I’ll come (to you) in half an hour,” but it doesn’t include the idea of going back; for “I’ll be back,” prefer voltar or regressar.

Can I say estarei de volta to match English I’ll be back?

You can: Estarei de volta daqui a meia hora. It’s correct but more formal/announced-sounding. In everyday EP, Volto… or Vou voltar… is shorter and more idiomatic. For very short absences, Volto já is the go‑to phrase — Be right back.

Do I need an article before hora? Could I say uma meia hora?

Standard: meia hora (no article).
uma meia hora means “about half an hour/a good half hour” and is less common, slightly colloquial. Avoid a meia hora here; that would refer to a specific half-hour block, not the duration from now.

Where does the time phrase go? Can I front it?

Yes. All are fine, with slight emphasis differences:

Volto em/daqui a/dentro de meia hora.
Daqui a meia hora, volto. Fronting the time gives it extra emphasis.

How would I say “for half an hour” (duration), not “in half an hour” (future point)?

Use no preposition or use durante/por:

Esperei meia hora. (I waited for half an hour.)
Esperei durante/por meia hora. Don’t use em for this meaning.

What prepositions are usual with times like this in EP?

Future point from now: daqui a (most explicit), also em or dentro de.
Exact clock time: a/à(s) → Volto às sete.
Common contractions of em with articles: no/na/nos/nas and with indefinites num/numa (e.g., numa hora = em uma hora). Here there’s no article, so em meia hora doesn’t contract.

Any pronunciation tips for European Portuguese?

Approximate EP pronunciation:

Eu: ehw
volto: VÓL-too (dark L)
em: nasal ẽ (similar to French en)
meia: MAY-uh (often with a reduced first vowel in EP)
hora: Ó-ra (tapped r) Spoken fast, it flows like: ehw VÓL-too ẽ MAY-uh Ó-ra.

Is there any risk using logo here, like Volto logo?

In Portugal, Volto já is the set phrase for Be right back. Volto logo is understood as “I’ll be back soon,” which can be vaguer/longer depending on context. For a precise time, prefer daqui a meia hora, em meia hora, or dentro de meia hora.

Any closely related alternatives I should know in Portugal?

Daqui a bocado/pouco, volto. = I’ll be back in a bit.
Regresso daqui a meia hora. = Slightly more formal.
Volto pelas sete. = I’ll be back around seven (for vague clock times).