Suponho que ele esteja perto.

Because suponho que often triggers the subjunctive in Portuguese.

In Suponho que ele esteja perto, the speaker is expressing an assumption, not a confirmed fact. Portuguese commonly uses the subjunctive after expressions of doubt, uncertainty, possibility, assumption, or emotion.

So:

• Suponho que ele está perto = less standard in careful grammar, though you may hear similar patterns in casual speech
• Suponho que ele esteja perto = standard and grammatically expected

A good rule of thumb is:

• certainty/fact → often indicative
• uncertainty/assumption → often subjunctive

Esteja is the present subjunctive form of estar.

Here is the present subjunctive of estar:

• eu esteja
• você/ele/ela esteja
• nós estejamos
• vocês/eles/elas estejam

In your sentence, ele esteja means he be in the subjunctive sense, which in natural English is usually translated as he is after verbs like I suppose, I doubt, I hope, etc.

Because suponho means something like I suppose, I assume, or I imagine, and that introduces an idea that is not fully established as fact.

Portuguese often uses the subjunctive after clauses introduced by que when the main clause shows:

• doubt
• uncertainty
• assumption
• emotion
• desire
• possibility

Examples:

• Duvido que ele venha. = I doubt he is coming / will come.
• Espero que ele esteja bem. = I hope he is well.
• Suponho que ele esteja perto. = I suppose he is nearby.

That said, usage can vary in everyday speech, but for learners, the safest and most standard choice after suponho que is the subjunctive.

The difference is mainly certainty.

• Ele está perto. = He is near / nearby.
  This sounds like a statement of fact.

• Suponho que ele esteja perto. = I suppose he is near / nearby.
  This shows the speaker is making an inference or assumption.

So the second sentence is less direct and less certain.

Because perto describes a location or temporary position, and Portuguese normally uses estar for that.

• estar = state, location, condition
• ser = identity, essential characteristics, time, origin, etc.

So:

• Ele está perto. = He is near.
• Ele é... would not work with perto in this meaning.

This follows the usual pattern that physical location takes estar.

Perto means near, close, or nearby.

In this sentence, it most naturally means nearby or close in location:

• Suponho que ele esteja perto. = I suppose he is nearby.

It can also be used more specifically with de:

• Ele está perto de casa. = He is near home.
• O hotel fica perto da praia. = The hotel is near the beach.

Without de + place/person/thing, perto can stand alone and simply mean nearby.

Because perto can be used in two ways:

1. On its own, meaning nearby

   • Ele está perto. = He is nearby.

2. With de, meaning near to something

   • Ele está perto de casa. = He is near home.

In Suponho que ele esteja perto, the idea is complete without naming what he is near, so de is not needed.

Yes, you often can, especially if the subject is clear from context.

Portuguese frequently omits subject pronouns when the meaning is understood. However, in this sentence, keeping ele can help avoid ambiguity, because esteja could refer to different third-person subjects depending on context:

• Suponho que esteja perto. = I suppose he/she/it/you is near, depending on context
• Suponho que ele esteja perto. = clearly he

So omitting ele is possible, but including it makes the sentence clearer.

Yes, but it can sound a little more thoughtful, formal, or bookish than some everyday alternatives, depending on context.

Common alternatives include:

• Acho que ele está por perto. = I think he’s around.
• Imagino que ele esteja perto. = I imagine he’s nearby.
• Creio que ele esteja perto. = I believe he’s nearby.
• Deve estar por perto. = He must be around / He’s probably nearby.

So suponho is perfectly correct and natural, but in casual spoken Brazilian Portuguese, many people might more often say acho or imagino.

Not normally in everyday Portuguese.

The standard structure is:

• Suponho que ele esteja perto.

Portuguese usually uses que + conjugated verb after verbs like suponho, acho, imagino, espero, etc.

A structure like Suponho ele estar perto sounds unnatural in normal conversation and writing. Stick with que here.

In Brazilian Portuguese, esteja is roughly pronounced like:

es-TEH-zha or es-TEY-zha, depending on accent

A few helpful points:

• es sounds like es in mess, though unstressed vowels can be lighter
• tej has a teh or slightly tey sound
• j in Portuguese sounds like the s in measure or the zh sound

So esteja is approximately:

• ehs-TEH-zhah

The stress falls on TEI/TEH: es-TE-ja

It is neutral to slightly formal.

• Suponho que ele esteja perto. sounds correct, educated, and natural.
• In casual everyday speech, many Brazilians might say something simpler like:
  • Acho que ele está perto.
  • Acho que ele está por perto.

So the sentence is not overly formal, but it is a bit more polished than very casual speech.

They are very similar, but por perto often sounds a little more like around here or somewhere nearby, while perto can sound more directly near/close.

Compare:

• Ele está perto. = He is near / close.
• Ele está por perto. = He is around nearby / somewhere close by.

So if you want a slightly more conversational sentence, you could also say:

• Suponho que ele esteja por perto.

That sounds very natural in Brazilian Portuguese.