No sé si merece la pena ir tan pronto si la oficina abre a las diez.

Merecer la pena is a fixed expression meaning to be worth it.

So in this sentence, merece la pena ir tan pronto means it is worth going so early.

Literally, pena can mean pain, trouble, sorrow, or effort, but in this expression you should learn the whole chunk merecer la pena as one unit.

They do two different jobs.

• The first si means whether / if and introduces an indirect question:

  • No sé si merece la pena...
  • I don’t know whether it’s worth it...

• The second si means if and introduces a condition or reason:

  • ...si la oficina abre a las diez
  • ...if the office opens at ten

So the structure is basically:

I don’t know whether X, if Y.

That may feel a bit repetitive to an English speaker, but it is completely normal in Spanish.

Because after merece la pena, Spanish often uses an infinitive to say what action is or is not worth doing.

The pattern is:

merece la pena + infinitive

Examples:

• Merece la pena esperar.
• No merece la pena discutir.
• Merece la pena ir temprano.

So here:

• merece la pena ir tan pronto = it’s worth going so early

You only use a conjugated verb if you build the sentence differently.

Here it means so early.

Pronto can mean soon or early, depending on context. Since the sentence is about going to an office before it opens, tan pronto is understood as so early.

Also, tan means so before an adjective or adverb:

• tan pronto = so early / so soon
• tan tarde = so late
• tan rápido = so fast

A very natural alternative would be tan temprano, which many learners may find easier to connect to early.

A quick comparison:

• pronto = early / soon
• temprano = early
• muy pronto = very early / very soon
• tan pronto = so early / so soon

The key difference between muy and tan is:

• muy = very
• tan = so

So:

• muy pronto = very early
• tan pronto = so early

In this sentence, tan sounds natural because the speaker is reacting to the time and comparing it with the office opening at ten.

Because si meaning whether normally takes the indicative, not the subjunctive.

So these are normal:

• No sé si viene.
• No sé si merece la pena.
• No sé si abre a las diez.

This is a very common point for English speakers, because they often expect uncertainty to trigger the subjunctive. But after no sé si, standard Spanish usually uses the indicative.

Because Spanish often uses the present indicative for scheduled or timetabled future events.

So:

• La oficina abre a las diez = The office opens at ten

This is very similar to English:

• My train leaves at six
• The shop opens at nine

You could also hear other future forms in different contexts, but the present is very natural here.

To say the time something happens, Spanish uses a la or a las.

• a la una = at one
• a las dos = at two
• a las diez = at ten

So la oficina abre a las diez means the office opens at ten o’clock.

Yes. Vale la pena also means it’s worth it.

Both are correct and widely understood. A useful general note is:

• merece la pena is very common in Spain
• vale la pena is also common, especially in much of Latin America

In many situations they are interchangeable:

• No sé si merece la pena ir tan pronto
• No sé si vale la pena ir tan pronto

It is the same word, but the meaning works differently inside the expression.

• Qué pena means something like what a shame
• merecer la pena is a fixed idiom meaning to be worth it

So even though the word is the same, in this sentence you should not translate pena by itself. Learn merecer la pena as one whole expression.

Normally, no.

Si la oficina abre a las diez is closely connected to the main idea, so Spanish usually writes it without a comma:

• No sé si merece la pena ir tan pronto si la oficina abre a las diez.

A comma could change the rhythm or make it feel more marked, but the standard version without a comma is the natural one.

Because sé here is the first-person singular form of saber:

• yo sé = I know

It has a written accent to distinguish it from se, the unstressed pronoun:

• No sé = I don’t know
• Se llama Ana = Her name is Ana

So the accent is important.

Yes, it sounds natural.

A speaker from Spain might also say:

• No sé si merece la pena ir tan temprano si la oficina abre a las diez.

That version may feel slightly clearer to learners because temprano is more obviously connected to early, but tan pronto is also perfectly possible.

So the original sentence is idiomatic and natural in Peninsular Spanish.